Infant mortality

Medicine and biology

Causes of infant mortality and deaths that are related to medical conditions include: low birth weight, sudden infant death syndrome, malnutrition, congenital malformations, and infectious diseases, low income for health care including neglected tropical diseases.

The American Academy of Pediatrics recommends that infants need multiple doses of vaccines such as diphtheria-tetanus-acellular pertussis vaccine, Haemophilus influenzae type b (Hib) vaccine, Hepatitis B (HepB) vaccine, inactivated polio vaccine (IPV), and pneumococcal vaccine (PCV). Research was conducted by the Institute of Medicine's Immunization Safety Review Committee concluded that there is no relationship between these vaccines and risk of SIDS in infants.

Premature birth

Premature, or preterm birth (PTB) is defined as birth before 37 weeks of gestation and can be further sub-classified as extremely PTB (occurring at less than 28 weeks gestation), very preterm birth (occurring between 28 and 32 weeks gestation), and moderate to late PTB (occurring from 32 through 36 weeks gestation). Lower gestational age increases the risk of infant mortality.^[23]

Over the last decade, prematurity has been the leading cause of worldwide mortality for neonates and children under the age of five. The overall PTB mortality rate in 2010 was 11.1% (15 million deaths) worldwide and was highest in low to middle income countries in sub-Saharan Africa and south Asia (60% of all PTBs), compared with high income countries in Europe, or the United States.^[24] Low income countries also have limited resources to care for the needs of preterm infants, which increases the risk of infant mortality. The survival rate in these countries, for infants born before 28 weeks of gestation is 10%, compared with a 90% survival rate in high income countries.^[25]

Premature birth can be either spontaneous, or medically induced. The risk of spontaneous PTB increases with "extremes of maternal age (both young and old), short interpregnancy interval, multiple gestation, assisted reproductive technology, prior PTB, family history, substance abuse, cigarette use, low maternal socioeconomic status, late or no prenatal care, low maternal prepregnancy weight, bacterial vaginosis, periodontal disease, and poor pregnancy weight gain."^[26] Medically induced PTB are often conducted when continued pregnancy poses significant risks to the mother, or fetus. The most common attributing factors for medically induced PTB include preeclampsia, diabetes, maternal medical conditions, and fetal distress, or developmental problems.^[27] Despite these risk factors, the underlying causes of premature infant death are often unknown and approximately 65% of all cases are not associated with any known risk factor.^[23]

Understanding the biological causes and predictors is important for identifying and preventing premature birth and infant mortality. While the exact mechanisms responsible for inducing premature birth are often unknown, many of the underlying risk factors are associated with inflammation. Approximately "80% preterm births that occur at <1000 g or at <28 to 30 weeks of gestation" have been associated with inflammation. Biomarkers of inflammation, including C-reactive protein, ferritin, various interleukins, chemokines, cytokines, defensins and bacteria have been shown to be associated with increased risks of infection or inflammation-related preterm birth. Biological fluids have been utilized to analyze these markers in hopes of understand the pathology of preterm birth, but are not always useful if not acquired at the appropriate gestational time-frame. For example, biomarkers such as fibronectihn are accurate predictors of premature birth at over 24 weeks gestation, but have a poor predictive values before then.^[28]

Sudden infant death syndrome

Sudden infant death syndrome (SIDS) is a syndrome where an infant dies in their sleep with no reason behind it. Even with a complete autopsy, no one has been able to figure out what causes this disease. This disease is more common in Western countries.^[29] So much so, the United States Center for Disease Control reports Sudden Infant Death Syndrome to be the leading cause of death in infants age 1 month to 1 year of life.^[30] Even though researchers are not sure what causes this disease, they have discovered that it is healthier for babies to sleep on their backs instead of their stomachs.^[31] This discovery saved many families from the tragedy that this disease causes. Scientists have also discovered three causes within a model they created called "the contemporary triple risk model". This model states that three conditions such as the mother smoking while pregnant, the age of the infant, and stress referring to conditions such as overheating, prone sleeping, co-sleeping, and head covering.^[29] In the early 1990s, it was argued immunizations could attribute to an increased risk of Sudden Infant Death Syndrome; however, studies since then have proven otherwise and in fact support the idea that vaccinations provide protective properties by reducing the risk of Sudden Infant Death Syndrome.^[32]

In the United States, approximately 3500 infants deaths are attributed to sleep related deaths included in this category is Sudden Infant Death Syndrome.^[33] For this reason, the American Academy of Pediatrics recommends providing infants with safe-sleeping environments; additionally for the reductions of these sleep related mortalities, they recommend the prevention of the following, respectively, while pregnant or around infants: exposure to smoke, alcohol, and illicit drugs - this includes second hand smoking.^[33] They do however recommend the following do's: do breastfeed, do schedule immunizations according to proper immunization scheduling, and do use a pacifier.^[33]

Congenital malformations

Congenital malformations are birth defects that babies are born with, such as cleft lip and palate,Down Syndrome, and heart defects. Some congenital malformations may be more likely when the mother consumes alcohol, but can also be caused by genetics or unknown factors.^[34] Congenital malformations have had a significant impact on infant mortality. Malnutrition and infectious diseases were the main cause of death in more undeveloped countries. In the Caribbean and Latin America, congenital malformations only accounted for 5% of infant deaths, while malnutrition and infectious diseases accounted for 7% to 27% of infants deaths in the 1980s.^[35] In more developed countries such as the United States, there was a rise in infant deaths due to congenital malformations. These birth defects were mostly due to heart and central nervous system problems. In the 19th century, there was a decrease in the number of infant deaths from heart diseases. From 1979 to 1997, there was a 39% decline in infant mortality due to heart problems.^[36]

Low birth weight

Low birth weight makes up 60–80% of the infant mortality rate in developing countries. The New England Journal of Medicine stated that "The lowest mortality rates occur among infants weighing 3,000 to 3,500 g (6.6 to 7.7 lb). For infants born weighing 2,500 g (5.5 lb) or less, the mortality rate rapidly increases with decreasing weight, and most of the infants weighing 1,000 g (2.2 lb) or less die. As compared with normal-birth-weight infants, those with low weight at birth are almost 40 times more likely to die in the neonatal period; for infants with very low weight at birth the relative risk of neonatal death is almost 200 times greater." Infant mortality due to low birth weight is usually a direct cause stemming from other medical complications such as preterm birth, poor maternal nutritional status, lack of prenatal care, maternal sickness during pregnancy, and an unhygienic home environments.^[17] Along with birth weight, period of gestation makes up the two most important predictors of an infant's chances of survival and their overall health.^[37]

According to the New England Journal of Medicine, "in the past two decades, the infant mortality rate (deaths under one year of age per thousand live births) in the United States has declined sharply." Low birth weights from African American mothers remain twice as high as that of white women. LBW may be the leading cause of infant deaths, and it is greatly preventable. Although it is preventable, the solutions may not be the easiest but effective programs to help prevent LBW are a combination of health care, education, environment, mental modification and public policy, influencing a culture supporting lifestyle.^[38] Preterm birth is the leading cause of newborn deaths worldwide.^[39] Even though America excels past many other countries in the care and saving of premature infants, the percentage of American woman who deliver prematurely is comparable to those in developing countries. Reasons for this include teenage pregnancy, increase in pregnant mothers over the age of thirty-five, increase in the use of in-vitro fertilization which increases the risk of multiple births, obesity and diabetes. Also, women who do not have access to health care are less likely to visit a doctor, therefore increasing their risk of delivering prematurely.^[40]

Malnutrition

Percentage of population suffering from hunger, World Food Programme, 2020.

  < 2,5%

  < 5,0%

  5,0–14,9%

  15,0–24,9%

  25,0–34,9%

  > 35,0%

  No data

Malnutrition or undernutrition is defined as inadequate intake of nourishment, such as proteins and vitamins, which adversely affects the growth, energy and development of people all over the world.^[41] It is especially prevalent in women and infants under 5 who live in developing countries within the poorer regions of Africa, Asia, and Latin America.^[42] Children are most vulnerable as they have yet to fully develop a strong immune system, as well as being dependent upon parents to provide the necessary food and nutritional intake. It is estimated that about 3.5 million children die each year as a result of childhood or maternal malnutrition, with stunted growth, low body weight and low birth weight accounting for about 2.2 million associated deaths.^[43] Factors which contribute to malnutrition are socioeconomic, environmental, gender status, regional location, and breastfeeding cultural practices.^[44] It is difficult to assess the most pressing factor as they can intertwine and vary among regions.

Adverse effects of malnutrition

Children suffering from malnutrition face adverse physical effects such as stunting, wasting, or being overweight.^[45] Such characteristics entail difference in weight-and-height ratios for age in comparison to adequate standards. In Africa the number of stunted children has risen, while Asia holds the most children under 5 suffering from wasting.^[46] The number of overweight children has increased among all regions of the globe.^[46] Inadequate nutrients adversely effect physical and cognitive developments, increasing susceptibility to severe health problems. Micronutrient deficiency such as iron has been linked to children with anemia, fatigue, and poor brain development.^[45] Similarly, the lack of Vitamin A is the leading cause of blindness among malnourished children.^[45] The outcome of malnutrition in children results in decreased ability of the immune system to fight infections, resulting in higher rates of death from diseases such as malaria, respiratory disease and diarrhea.^[47]

Infectious diseases

Babies born in low to middle income countries in sub-Saharan Africa and southern Asia are at the highest risk of neonatal death. Bacterial infections of the bloodstream, lungs, and the brain's covering (meningitis) are responsible for 25% of neonatal deaths. Newborns can acquire infections during birth from bacteria that are present in their mother's reproductive tract. The mother may not be aware of the infection, or she may have an untreated pelvic inflammatory disease or sexually transmitted disease. These bacteria can move up the vaginal canal into the amniotic sac surrounding the baby. Maternal blood-borne infection is another route of bacterial infection from mother to baby. Neonatal infection is also more likely with the premature rupture of the membranes (PROM) of the amniotic sac.^[48]

Seven out of ten childhood deaths are due to infectious diseases: acute respiratory infection, diarrhea, measles, and malaria. Acute respiratory infection such as pneumonia, bronchitis, and bronchiolitis account for 30% of childhood deaths; 95% of pneumonia cases occur in the developing world. Diarrhea is the second-largest cause of childhood mortality in the world, while malaria causes 11% of childhood deaths. Measles is the fifth-largest cause of childhood mortality.^[17][49] Folic acid for mothers is one way to combat iron deficiency. A few public health measures used to lower levels of iron deficiency anemia include iodize salt or drinking water, and include vitamin A and multivitamin supplements into a mother's diet.^[17] A deficiency of this vitamin causes certain types of anemia (low red blood cell count).^[50]

Environmental

Infant mortality rate can be a measure of a nation's health and social condition.^[37][51] It is a composite of a number of component rates which have their separate relationship with various social factors and can often be seen as an indicator to measure the level of socioeconomic disparity within a country.^[51]

Organic water pollution is a better indicator of infant mortality than health expenditures per capita. Water contaminated with various pathogens houses a host of parasitic and microbial infections. Infectious disease and parasites are carried via water pollution from animal wastes.^[52] Areas of low socioeconomic status are more prone to inadequate plumbing infrastructure, and poorly maintained facilities.^[17] The burning of inefficient fuels doubles the rate of children under 5 years old with acute respiratory tract infections.^[17] Climate and geography often play a role in sanitation conditions. For example, the inaccessibility of clean water exacerbates poor sanitation conditions.^[52]

People who live in areas where particulate matter (PM) air pollution is higher tend to have more health problems across the board. Short-term and long-term effects of ambient air pollution are associated with an increased mortality rate, including infant mortality. Air pollution is consistently associated with post neonatal mortality due to respiratory effects and sudden infant death syndrome. Specifically, air pollution is highly associated with SIDs in the United States during the post-neonatal stage.^[53] High infant mortality is exacerbated because newborns are a vulnerable subgroup that is affected by air pollution.^[54] Newborns who were born into these environments are no exception. Women who are exposed to greater air pollution on a daily basis who are pregnant should be closely watched by their doctors, as well as after the baby is born. Babies who live in areas with less air pollution have a greater chance of living until their first birthday. As expected, babies who live in environments with more air pollution are at greater risk for infant mortality. Areas that have higher air pollution also have a greater chance of having a higher population density, higher crime rates and lower income levels, all of which can lead to higher infant mortality rates.^[55]

The key pollutant for infant mortality rates is carbon monoxide. Carbon monoxide is a colorless, odorless gas that does great harm especially to infants because of their immature respiratory system.^[56] Another major pollutant is second-hand smoke, which is a pollutant that can have detrimental effects on a fetus. According to the American Journal of Public Health, "in 2006, more than 42 000 Americans died of second hand smoke-attributable diseases, including more than 41 000 adults and nearly 900 infants ... fully 36% of the infants who died of low birth weight caused by exposure to maternal smoking in utero were Blacks, as were 28% of those dying of respiratory distress syndrome, 25% dying of other respiratory conditions, and 24% dying of sudden infant death syndrome." The American Journal of Epidemiology also stated that "Compared with nonsmoking women having their first birth, women who smoked less than one pack of cigarettes per day had a 25% greater risk of mortality, and those who smoked one or more packs per day had a 56% greater risk. Among women having their second or higher birth, smokers experienced 30% greater mortality than nonsmokers."

Modern research in the United States on racial disparities in infant mortality suggests a link between the institutionalized racism that pervades the environment and high rates of African American infant mortality. In synthesis of this research, it has been observed that "African American infant mortality remains elevated due to the social arrangements that exist between groups and the lifelong experiences responding to the resultant power dynamics of these arrangements."^[22]

It is important to note that infant mortality rates do not decline among African Americans even if their socio-economic status does improve. Parker Dominguez at the University of Southern California has made some headway in determining the reasoning behind this, claiming black women are more prone to psychological stress than other women of different races in the United States. Stress is a lead factor in inducing labor in pregnant women, and therefore high levels of stress during pregnancy could lead to premature births that have the potential to be fatal for the infant.^[57]

Early childhood trauma

Early childhood trauma includes physical, sexual, and psychological abuse of a child ages zero to five years-old. Trauma in early development has extreme impact over the course of a lifetime and is a significant contributor to infant mortality. Developing organs are fragile. When an infant is shaken, beaten, strangled, or raped the impact is exponentially more destructive than when the same abuse occurs in a fully developed body. Studies estimate that 1–2 per 100,000 U.S. children annually are fatally injured. Unfortunately, it is reasonable to assume that these statistics underrepresent actual mortality.^[58][59] Three-quarters (70.6 percent) of child fatalities in FFY 2018 involved children younger than 3 years, and children younger than 1 year accounted for 49.4 percent of all fatalities.^[58] In particular, correctly identifying deaths due to neglect is problematic, and children with sudden unexpected death or those with what appear to be unintentional causes on the surface often have preventable risk factors which are substantially similar to those in families with maltreatment.

There is a direct relationship between age of maltreatment/injury and risk for death. The younger an infant is, the more dangerous the maltreatment.^[60]

Family configuration,^[61][62] child gender, social isolation, lack of support, maternal youth, marital status, poverty, parental ACES, and parenting practices^[63] are thought to contribute to increased risk.^[58]

Socio-economic factors

Infant mortality rates are higher in countries with higher economic inequality

Social class is a major factor in infant mortality, both historically and today. Between 1912 and 1915, the Children's Bureau in the United States examined data across eight cities and nearly 23,000 live births. They discovered that lower incomes tend to correlate with higher infant mortality. In cases where the father had no income, the rate of infant mortality was 357% more than that for the highest income earners ($1,250+). Differences between races were also apparent. African-American mothers experience infant mortality at a rate 44% higher than average;^[64] however, research indicates that socio-economic factors do not totally account for the racial disparities in infant mortality.^[22]

While infant mortality is normally negatively correlated with GDP, there may indeed be some opposing short-term effects from a recession. A recent study by The Economist showed that economic slowdowns reduce the amount of air pollution, which results in a lower infant mortality rate. In the late 1970s and early 1980s, the recession's impact on air quality is estimated to have saved around 1,300 US babies.^[65] It is only during deep recessions that infant mortality increases. According to Norbert Schady and Marc-François Smitz, recessions when GDP per capita drops by 15% or more increase infant mortality.^[66]

Social class dictates which medical services are available to an individual. Disparities due to socioeconomic factors have been exacerbated by advances in medical technology. Developed countries, most notably the United States, have seen a divergence between those living in poverty who cannot afford medical advanced resources, leading to an increased chance of infant mortality, and others.^[51]

Countries by 2019 GDP (nominal) per capita.^[67]

Political modernization perspective, the neo-classical economic theory that scarce goods are most effectively distributed to the market, say that the level of political democracy influences the rate of infant mortality. Developing nations with democratic governments tend to be more responsive to public opinion, social movements, and special interest groups for issues like infant mortality. In contrast, non-democratic governments are more interested in corporate issues and less so in health issues. Democratic status effects the dependency a nation has towards its economic state via export, investments from multinational corporations and international lending institutions.^[68]

Levels of socioeconomic development and global integration are inversely related to a nation's infant mortality rate.^[17][69] Dependency perspective occurs in a global capital system. A nation's internal impact is highly influenced by its position in the global economy and has adverse effects on the survival of children in developing countries.^[52] Countries can experience disproportionate effects from its trade and stratification within the global system.^[70] It aids in the global division of labor, distorting the domestic economy of developing nations. The dependency of developing nations can lead to a reduce rate of economic growth, increase income inequality inter- and intra-national, and adversely affects the wellbeing of a nation's population. A collective cooperation between economic countries plays a role in development policies in the poorer, peripheral, countries of the world.^[68]

These economic factors present challenges to governments' public health policies.^[52] If the nation's ability to raise its own revenues is compromised, governments will lose funding for its health service programs, including services that aim in decreasing infant mortality rates.^[68] Peripheral countries face higher levels of vulnerability to the possible negative effects of globalization and trade in relation to key countries in the global market.^[52]

Even with a strong economy and economic growth (measured by a country's gross national product), the advances of medical technologies may not be felt by everyone, lending itself to increasing social disparities.^[51] In England from 2014 to 2017 a rise in infant mortality was experienced disproportionately in the most deprived local authorities where the previously declining trend in infant mortality was reversed with an additional 24 infant deaths per 100,000 live births per year relative to the previous trend^[71]

War

In policy, there is a lag time between realization of a problem's possible solution and actual implementation of policy solutions.^[72] Infant mortality rates correlate with war, political unrest, and government corruption.^[17]

In most cases, war-affected areas will experience a significant increase in infant mortality rates. Having a war taking place where a woman is planning on having a baby is not only stressful on the mother and foetus, but also has several detrimental effects.

However, many other significant factors influence infant mortality rates in war-torn areas. Health care systems in developing countries in the midst of war often collapse. Attaining basic medical supplies and care becomes increasingly difficult. During the Yugoslav Wars in the 1990s Bosnia experienced a 60% decrease in child immunizations. Preventable diseases can quickly become epidemic given the medical conditions during war.^[73]

Many developing countries rely on foreign aid for basic nutrition. Transport of aid becomes significantly more difficult in times of war. In most situations the average weight of a population will drop substantially.^[74] Expecting mothers are affected even more by lack of access to food and water. During the Yugoslav Wars in Bosnia the number of premature babies born increased and the average birth weight decreased.^[73]

There have been several instances in recent years of systematic rape as a weapon of war. Women who become pregnant as a result of war rape face even more significant challenges in bearing a healthy child. Studies suggest that women who experience sexual violence before or during pregnancy are more likely to experience infant death in their children.^[75][76][77] Causes of infant mortality in abused women range from physical side effects of the initial trauma to psychological effects that lead to poor adjustment to society. Many women who became pregnant by rape in Bosnia were isolated from their hometowns making life after childbirth exponentially more difficult.^[78]

Culture

High rates of infant mortality occur in developing countries where financial and material resources are scarce and there is a high tolerance to high number of infant deaths. There are circumstances where a number of developing countries to breed a culture where situations of infant mortality such as favoring male babies over female babies are the norm.^[17] In developing countries such as Brazil, infant mortality rates are commonly not recorded due to failure to register for death certificates.^[79] Failure to register is mainly due to the potential loss of time and money and other indirect costs to the family.^[79] Even with resource opportunities such as the 1973 Public Registry Law 6015, which allowed free registration for low-income families, the requirements to qualify hold back individuals who are not contracted workers.^[79]

Another cultural reason for infant mortality, such as what is happening in Ghana, is that "besides the obvious, like rutted roads, there are prejudices against wives or newborns leaving the house."^[80] Because of this it is making it even more difficult for the women and newborns to get the treatment that is available to them and that is needed.

Cultural influences and lifestyle habits in the United States can account for some deaths in infants throughout the years. According to the Journal of the American Medical Association "the post neonatal mortality risk (28 to 364 days) was highest among continental Puerto Ricans" compared to babies of the non-Hispanic race. Examples of this include teenage pregnancy, obesity, diabetes and smoking. All are possible causes of premature births, which constitute the second highest cause of infant mortality.^[40] Ethnic differences experienced in the United States are accompanied by higher prevalence of behavioral risk factors and sociodemographic challenges that each ethnic group faces.^[37]

Birth spacing

Map of countries by fertility rate (2020), according to the Population Reference Bureau

Birth spacing is the time between births. Births spaced at least three years apart from one another are associated with the lowest rate of mortality. The longer the interval between births, the lower the risk for having any birthing complications, and infant, childhood and maternal mortality.^[18][82] Higher rates of pre-term births, and low birth weight are associated with birth to conception intervals of less than six months and abortion to pregnancy interval of less than six months. Shorter intervals between births increase the chances of chronic and general under-nutrition; 57% of women in 55 developing countries reported birth spaces shorter than three years; 26% report birth spacing of less than two years. Only 20% of post-partum women report wanting another birth within two years; however, only 40% are taking necessary steps such as family planning to achieve the birth intervals they want.^[18]

Unplanned pregnancies and birth intervals of less than twenty-four months are known to correlate with low birth weights and delivery complications. Also, women who are already small in stature tend to deliver smaller than average babies, perpetuating a cycle of being underweight.^[17][18][82]

Policy

Reductions in infant mortality are possible in any stage of a country's development.^[21] Rate reductions are evidence that a country is advancing in human knowledge, social institutions and physical capital. Governments can reduce the mortality rates by addressing the combined need for education (such as universal primary education), nutrition, and access to basic maternal and infant health services. A policy focus has the potential to aid those most at risk for infant and childhood mortality allows rural, poor and migrant populations.^[72]

Reducing chances of babies being born at low birth weights and contracting pneumonia can be accomplished by improving air quality. Improving hygiene can prevent infant mortality. Home-based technology to chlorinate, filter, and solar disinfection for organic water pollution could reduce cases of diarrhea in children by up to 48%.^[17][49][52] Improvements in food supplies and sanitation has been shown to work in the United States' most vulnerable populations, one being African Americans. Overall, women's health status need to remain high.^[51]

Promoting behavioral changes, such as hand washing with soap, can significantly reduce the rate of infant mortality from respiratory and diarrheal diseases.^[83] According to UNICEF, hand washing with soap before eating and after using the toilet can save more lives of children by cutting deaths from diarrhea and acute respiratory infections.^[84]

Focusing on preventing preterm and low birth weight deliveries throughout all populations can help to eliminate cases of infant mortality and decrease health care disparities within communities. In the United States, these two goals have decreased infant mortality rates on a regional population, it has yet to see further progress on a national level.^[37]

Increasing human resources such as physicians, nurses, and other health professionals will increase the number of skilled attendants and the number of people able to give out immunized against diseases such as measles. Increasing the number of skilled professionals is negatively correlated with maternal, infant, and childhood mortality. With the addition of one physician per 10,000 people, there is a potential for 7.08 fewer infant deaths per 10,000.^[85]

In certain parts of the U.S., specific modern programs aim to reduce levels of infant mortality. One such program that aims to reduce infant mortality is the "Best Babies Zone" (BBZ) based at the University of California, Berkeley. The BBZ uses the life course approach to address the structural causes of poor birth outcomes and toxic stress in three U.S. neighborhoods. By employing community-generated solutions, the Best Babies Zone's ultimate goal is to achieve health equity in communities that are disproportionately impacted by infant death.^[86]

Prenatal care and maternal health

When a woman becomes pregnant, certain steps can help to reduce the chance of complications during the pregnancy. Attending regular prenatal care check-ups will help improve the baby's chances of being delivered in safer conditions and surviving.^[87] Additionally, taking supplementation, including folic acid, can help reduce the chances of birth defects, a leading cause of infant mortality.^[88] Many countries have instituted mandatory folic acid supplementation in their food supply, which has significantly reduced the occurrence of spina bifida, a birth defect, in newborns.^[89] Similarly, the fortification of salt with iodine, salt iodization, has helped reduce adverse birth outcomes associated with low iodine levels during pregnancy.^[90]

Abstinence from alcohol can also decrease the chances of harm to the fetus during pregnancy. Drinking any amount of alcohol during pregnancy may lead to fetal alcohol spectrum disorders (FASD) or alcohol related birth defects (ARBD).^[91] Tobacco use during pregnancy has also been shown to significantly increase the risk of a preterm or low birth weight birth, both of which are leading causes of infant mortality.^[92] Pregnant women should consult with their doctors to best manage any existing health conditions that they have to avoid complications of both their health as well as the fetus. Obese women are at an increased risk of developing complications during pregnancy, including gestational diabetes or pre-eclampsia. Additionally, they are more likely to experience a pre-term birth or have a child with birth defects.^[93][90]

Nutrition

Appropriate nutrition for newborns and infants can help keep them healthy and avoid health complications during early childhood. The American Academy of Pediatrics recommends exclusively breastfeeding infants for the first 6 months of life, following by a combination of breastfeeding and other sources of food through the next 6 months of life, up to 1 year of age.^[94] Infants under 6 months of age who are exclusively breastfed have a lower risk of mortality compared to infants who receive a combination of breast milk and other food, as well as no breast milk at all.^[95] For this reason, breast feeding is favored over formula feeding by healthcare professionals.

Vaccinations

The Centers for Disease Control and Prevention (CDC) defines infants as those 1 month of age to 1 year of age.^[96] For these infants, the CDC recommends the following vaccinations: Hepatitis B (HepB), Rotavirus (RV), Haemophilus Influenzae type B (HIB), Pneumococcal Conjugate (PCV13), Inactivated Poliovirus (IPV < 18 yrs), Influenza, Varicella, Measles, Mumps, Rubella (MMR), and Diphtheria, tetanus, acellular pertussis (DTapP < 7yrs).^[97] Each of these vaccinations are given at particular age ranges depending on the vaccination and are required to be done in a series of 1 to 3 doses over time depending on the vaccination.^[97]

The efficacy of these vaccinations can be seen immediately following their introduction to society.^[98] Following the advent of the Pneumococcal Conjugate vaccine (PCV13) in the United States in the year 2000, the World Health Organization (WHO) reports studies done in 2004 had shown a 57% decline invasive penicillin-resistant strains of diseases and a 59% reduction in multiple antibiotic resistant strains that could lead to mortality among infants.^[98] This reduction was even greater for children under 2 years of age with studies finding an 81% reduction in those same strains.^[98]

As aforementioned in a previous section, Sudden Infant Death Syndrome is the leading cause of infant mortality for those 1 month of age to 1 year of age.^[30] Immunizations, when given in accordance to proper guidelines, have shown to reduce the risk of Sudden Infant Death Syndrome by 50%.^[33][99] For this reason, the American Academy of Pediatrics (AAP) and the Center for Disease Control (CDC) both recommend immunizations in accordance to their guidelines.^[33][100]

Socio-economic factors

It has been well documented that increased education among mothers, communities, and local health workers results in better family planning, improvement on children's health, and lower rates of children's deaths. High-risk areas, such as Sub-Saharan Africa, have demonstrated that an increase in women's education attainment leads to a reduction in infant mortality by about 35%.^[101] Similarly, coordinated efforts to train community health workers in diagnosis, treatment, malnutrition prevention, reporting and referral services has reduced infant mortality in children under 5 as much as 38%.^[102] Public health campaigns centered around the "First 1,000 Days" of conception have been successful in providing cost-effective supplemental nutrition programs, as well as assisting young mothers in sanitation, hygiene and breastfeeding promotion.^[103] Increased intake of nutrients and better sanitation habits have a positive impact on health, especially developing children. Educational attainment and public health campaigns provide the knowledge and means to practice better habits and leads to better outcomes against infant mortality rates.

Awareness of health services, education, and economic opportunities provide means to sustain and increase chance of development and survival. A decrease in GDP, for example, results in increased rates of infant mortality.^[104] Negative effects on household income reduces amount being spent on food and healthcare, affecting the quality of life and access to medical services to ensure full development and survival. On the contrary, increased household income translates to more access to nutrients and healthcare, reducing the risks associated with malnutrition and infant mortality.^[105] Moreover, increased aggregate household incomes will produce better health facilities, water and sewer infrastructures for the entire community.^[105]

Europe and USA

The exclusion of any high-risk infants from the denominator or numerator in reported IMRs can cause problems in making comparisons. Many countries, including the United States, Sweden and Germany, count an infant exhibiting any sign of life as alive, no matter the month of gestation or the size, but according to United States some other countries differ in these practices. All of the countries named adopted the WHO definitions in the late 1980s or early 1990s,^[118] which are used throughout the European Union.^[119] However, in 2009, the US CDC issued a report that stated that the American rates of infant mortality were affected by the United States' high rates of premature babies compared to European countries. It also outlined the differences in reporting requirements between the United States and Europe, noting that France, the Czech Republic, Ireland, the Netherlands, and Poland do not report all live births of babies under 500 g and/or 22 weeks of gestation.^{[120][121][122]} However, the differences in reporting are unlikely to be the primary explanation for the high rate of infant mortality in the United States' compared with its peer countries at a similar level of economic development. Rather, the report concluded that the primary reason for the United States’ higher infant mortality rate when compared with Europe was the United States’ much higher percentage of preterm births.^[122]

Until the 1990s, Russia and the Soviet Union did not count, as a live birth or as an infant death, extremely premature infants (less than 1,000 g, less than 28 weeks gestational age, or less than 35 cm in length) that were born alive (breathed, had a heartbeat, or exhibited voluntary muscle movement) but failed to survive for at least seven days.^[123] Although such extremely premature infants typically accounted for only about 0.5% of all live-born children, their exclusion from both the numerator and the denominator in the reported IMR led to an estimated 22%–25% lower reported IMR.^[124] In some cases, too, perhaps because hospitals or regional health departments were held accountable for lowering the IMR in their catchment area, infant deaths that occurred in the 12th month were "transferred" statistically to the 13th month (i.e., the second year of life), and thus no longer classified as an infant death.^[125][126]

Brazil

In certain rural developing areas, such as northeastern Brazil, infant births are often not recorded in the first place, resulting in the discrepancies between the infant mortality rate (IMR) and the actual number of infant deaths. Access to vital registry systems for infant births and deaths is an extremely difficult and expensive task for poor parents living in rural areas. Government and bureaucracies tend to show an insensitivity to these parents and their recent suffering from a lost child and produce broad disclaimers in the IMR reports that the information has not been properly reported, resulting in these discrepancies. Little has been done to address the underlying structural problems of the vital registry systems in respect to the lack of reporting from parents in rural areas, and in turn has created a gap between the official and popular meanings of child death.^[79] It is also argued that the bureaucratic separation of vital death recording from cultural death rituals is to blame for the inaccuracy of the infant mortality rate (IMR). Vital death registries often fail to recognize the cultural implications and importance of infant deaths. It is not to be said that vital registry systems are not an accurate representation of a region's socio-economic situation, but this is only the case if these statistics are valid, which is unfortunately not always the circumstance. "Popular death reporters" is an alternative method for collecting and processing statistics on infant and child mortality. Many regions may benefit from "popular death reporters" who are culturally linked to infants may be able to provide more accurate statistics on the incidence of infant mortality.^[79] According to ethnographic data, "popular death reporters" refers to people who had inside knowledge of anjinhos, including the grave-digger, gatekeeper, midwife, popular healers etc. —— all key participants in mortuary rituals.^[79] By combining the methods of household surveys, vital registries, and asking "popular death reporters" this can increase the validity of child mortality rates, but there are many barriers that can reflect the validity of our statistics of infant mortality. One of these barriers are political economic decisions. Numbers are exaggerated when international funds are being doled out; and underestimated during reelection.^[79]

The bureaucratic separation of vital death reporting and cultural death rituals stems in part due to structural violence.^[127] Individuals living in rural areas of Brazil need to invest large capital for lodging and travel in order to report infant birth to a Brazilian Assistance League office. The negative financial aspects deters registration, as often individuals are of lower income and cannot afford such expenses.^[79] Similar to the lack of birth reporting, families in rural Brazil face difficult choices based on already existing structural arrangements when choosing to report infant mortality. Financial constraints such as reliance on food supplementations may also lead to skewed infant mortality data.^[79]

In developing countries such as Brazil the deaths of impoverished infants are regularly unrecorded into the countries vital registration system; this causes a skew statistically. Culturally validity and contextual soundness can be used to ground the meaning of mortality from a statistical standpoint. In northeast Brazil they have accomplished this standpoint while conducting an ethnographic study combined with an alternative method to survey infant mortality.^[79] These types of techniques can develop quality ethnographic data that will ultimately lead to a better portrayal of the magnitude of infant mortality in the region. Political economic reasons have been seen to skew the infant mortality data in the past when governor Ceara devised his presidency campaign on reducing the infant mortality rate during his term in office. By using this new way of surveying, these instances can be minimized and removed, overall creating accurate and sound data.^[79]

United States

1906 headline imploring parents to attend to the cleanliness of their infants, and to expose them to the "clean air" outdoors.

Of the 27 most developed countries, the U.S. has the highest Infant Mortality Rate, despite spending much more on health care per capita.^[132] Significant racial and socio-economic differences in the United States affect the IMR, in contrast with other developed countries, which have more homogeneous populations. In particular, IMR varies greatly by race in the US. The average IMR for the whole country is therefore not a fair representation of the wide variations that exist between segments of the population. Many theories have been explored as to why these racial differences exist with socio economic factors usually coming out as a reasonable explanation. However, more studies have been conducted around this matter, and the largest advancement is around the idea of stress and how it affects pregnancy.^[133]

In the 1850s, the infant mortality rate in the United States was estimated at 216.8 per 1,000 babies born for whites and 340.0 per 1,000 for African Americans, but rates have significantly declined in the West in modern times. This declining rate has been mainly due to modern improvements in basic health care, technology, and medical advances.^[134] In the last century, the infant mortality rate has decreased by 93%.^[37] Overall, the rates have decreased drastically from 20 deaths in 1970 to 6.9 deaths in 2003 (per every 1000 live births). In 2003, the leading causes of infant mortality in the United States were congenital anomalies, disorders related to immaturity, AIDS, and maternal complications. Babies born with low birth weight increased to 8.1% while cigarette smoking during pregnancy declined to 10.2%. This reflected the amount of low birth weights concluding that 12.4% of births from smokers were low birth weights compared with 7.7% of such births from non-smokers.^[135] According to the New York Times, "the main reason for the high rate is preterm delivery, and there was a 10% increase in such births from 2000 to 2006." Between 2007 and 2011, however, the preterm birth rate has decreased every year. In 2011 there was an 11.73% rate of babies born before the 37th week of gestation, down from a high of 12.80% in 2006.^[136]

Economic expenditures on labor and delivery and neonatal care are relatively high in the United States. A conventional birth averages US$9,775 with a C-section costing US$15,041.^[137] Preterm births in the US have been estimated to cost $51,600 per child, with a total yearly cost of $26.2 billion.^[138] Despite this spending, several reports state that infant mortality rate in the United States is significantly higher than in other developed nations.^{[22][139][140]} Estimates vary; the CIA's World Factbook ranks the US 55th internationally in 2014, with a rate of 6.17, while the UN figures from 2005 to 2010 place the US 34th.

Aforementioned differences in measurement could play a substantial role in the disparity between the US and other nations. A non-viable live birth in the US could be registered as a stillbirth in similarly developed nations like Japan, Sweden, Norway, Ireland, the Netherlands, and France – thereby reducing the infant death count.^[122] Neonatal intensive care is also more likely to be applied in the US to marginally viable infants, although such interventions have been found to increase both costs and disability. A study following the implementation of the Born Alive Infant Protection Act of 2002 found universal resuscitation of infants born between 20 and 23 weeks increased the neonatal spending burden by $313.3 million while simultaneously decreasing quality-adjusted life years by 329.3.^[141]

Data indicating the IMR disparity between infants Non-Hispanic black mothers and infants of white or Hispanic mothers in the United States from 2000 to 2010.

The vast majority of research conducted in the late twentieth and early twenty-first century indicates that African-American infants are more than twice as likely to die in their first year of life than white infants. Although following a decline from 13.63 to 11.46 deaths per 1000 live births from 2005 to 2010, non-Hispanic black mothers continued to report a rate 2.2 times as high as that for non-Hispanic white mothers.^[142]

Contemporary research findings have demonstrated that nationwide racial disparities in infant mortality are linked to the experiential state of the mother and that these disparities cannot be totally accounted for by socio-economic, behavioral or genetic factors.^[22] The Hispanic paradox, an effect observed in other health indicators, appears in the infant mortality rate, as well. Hispanic mothers see an IMR comparable to non-Hispanic white mothers, despite lower educational attainment and economic status. A study in North Carolina, for example, concluded that "white women who did not complete high school have a lower infant mortality rate than black college graduates."^[143] According to Mustillo's CARDIA (Coronary Artery Risk Development in Young Adults) study, "self reported experiences of racial discrimination were associated with pre-term and low-birthweight deliveries, and such experiences may contribute to black-white disparities in prenatal outcomes."^[144] Likewise, dozens of population-based studies indicate that "the subjective, or perceived experience of racial discrimination is strongly associated with an increased risk of infant death and with poor health prospects for future generations of African Americans."^[22]

United Kingdom

A study published in the British Medical Journal in 2019 found that the rate of infant mortality in England had increased with an additional 24 infant deaths per 100 000 live births per year. There was no significant change from the pre-existing trend in the most affluent local authorities. The rise disproportionately affected the poorest areas of the country, and was attributed largely to rising child poverty, as a result of sustained reductions in the welfare benefits available to families with children.^[163]

United States

Decreases in infant mortality in given countries across the world during the 20th century have been linked to several common trends, scientific advancements, and social programs. Some of these include the state improving sanitation, improving access to healthcare, improving education, and the development of medical advancements such as penicillin, and safer blood transfusions.^[166]

In the United States, improving infant mortality in the early half of the 20th century meant tackling environmental factors. Improving sanitation, and especially access to safe drinking water, helped the United States dramatically decrease infant mortality, a growing concern in the United States since the 1850s.^[167] On top of these environmental factors, during this time the United States endeavored to increase education and awareness regarding infant mortality. Pasteurization of milk also helped the United States combat infant mortality in the early 1900s, a practice which allowed the United States to curb disease in infants.^[168] These factors, on top of a general increase in the standard of living for those living in urban settings, helped the United States make dramatic improvements in their rates of infant mortality in the early 20th century.

Although the overall infant mortality rate was sharply dropping during this time, within the United States infant mortality varied greatly among racial and socio-economic groups. The change in infant mortality from 1915 to 1933 was, for the white population, 98.6 in 1,000 to 52.8 in 1,000, and for the black population, 181.2 in 1,000 to 94.4 in 1,000. Studies imply that this has a direct correlation with relative economic conditions between these populations.^[169] Additionally, infant mortality in southern states was consistently 2% higher than other states in the US across a 20-year period from 1985. Southern states also tend to perform worse in predictors for higher infant mortality, such as per capita income and poverty rate.^[170]

In the latter half of the 20th century, a focus on greater access to medical care for women spurred declines in infant mortality in the United States. The implementation of Medicaid, granting wider access to healthcare, contributed to a dramatic decrease in infant mortality, in addition to access to greater access to legal abortion and family-planning care, such the IUD and the birth control pill.^[171]

In the decades following the 1970s, the United States' decreasing infant mortality rates began to slow, falling behind China's, Cuba's, and other developed countries'. Funding for the federally subsidized Medicaid and Maternal and Infant Care was sharply reduced, and availability of prenatal care greatly decreased for low-income parents.^[172]

China

The People's Republic of China's growth of medical resources in the latter half of the 20th century partly explains its dramatic improvement with regards to infant mortality during this time. Part of this increase included the adoption of the Rural Cooperative Medical System, which was founded in the 1950s. The Cooperative Medical System granted healthcare access to previously underserved rural populations, is estimated to have covered 90% of China's rural population throughout the 1960s. The Cooperative Medical System achieved an infant mortality rate of 25.09 per 1,000. The Cooperative Medical System was later defunded, leaving many rural populations to rely on an expensive fee-for-service system, although the rate continued to decline in general.^[173] This change in medical systems caused a socio-economic gap in accessibility to medical care in China, which fortunately was not reflected in its infant mortality rate of decline. Prenatal care was increasingly used, even as the Cooperative Medical System was replaced, and delivery assistance remained accessible.^[174]

China's one-child policy, adopted in the 1980s, negatively impacted its infant mortality. Women carrying unapproved pregnancies faced state consequences and social stigma and were thus less likely to use prenatal care. Additionally, economic realities and long-held cultural factors incentivized male offspring, leading some families who already had sons to avoid prenatal care or professional delivery services, and causing China to have unusually high female infant mortality rates during this time.^[175]