Pre-existing disease in pregnancy

Diabetes mellitus and pregnancy deals with the interactions of diabetes mellitus (not restricted to gestational diabetes) and pregnancy. Risks for the child include miscarriage, growth restriction, growth acceleration, fetal obesity (macrosomia), polyhydramnios and birth defects.

Thyroid disease in pregnancy can, if uncorrected, cause adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child. Demand for thyroid hormones is increased during pregnancy which may cause a previously unnoticed thyroid disorder to worsen. The most effective way of screening for thyroid dysfunction is not known.[3] A review found that more women were diagnosed with thyroid dysfunction when all pregnant women were tested instead of just testing those at 'high-risk' of thyroid problems (those with family history, signs or symptoms).[3] Finding more women with thyroid dysfunction meant that the women could have treatment and management through their pregnancies. However the outcomes of the pregnancies were surprisingly similar so more research is needed to look at the effects of screening all pregnant women for thyroid problems.[3]

Many infectious diseases have a risk of vertical transmission to the fetus, known as TORCH infections. Examples based on the TORCHES acronym include:

• Toxoplasma
• Other: Parvovirus B19, Zika, Chickenpox
• Rubella
• Cytomegalovirus
• Herpes simplex or Neonatal herpes simplex
• HIV[5][6]
• Syphilis[7]

Infections in pregnancy also raise particular concerns about whether or not to use drugs in pregnancy (that is, antibiotics or antivirals) to treat them. For example, pregnant women who contract H1N1 influenza infection are recommended to receive antiviral therapy with either oseltamivir (which is the preferred medication) or zanamivir.[8] Both amantadine and rimantadine have been found to be teratogenic and embryotoxic when given at high doses in animal studies.[8]

In pregnancy, changes in the levels of female sex hormones, such as estrogen, make a woman more likely to develop candidal vulvovaginitis. During pregnancy, the Candida fungus is more prevalent (common), and recurrent infection is also more likely.[9] There is no clear evidence that treatment of asymptomatic candidal vulvovaginitis in pregnancy reduces the risk of preterm birth.[10] Candidal vulvovaginitis in pregnancy should be treated with intravaginal clotrimazole or nystatin for at least 7 days.[11]

Bacterial vaginosis is an imbalance of naturally occurring bacterial flora in the vagina. Bacterial vaginosis occurring during pregnancy may increase the risk of pregnancy complications, most notably premature birth or miscarriage.[12] However, this risk is small overall and appears more significant in women who have had such complications in an earlier pregnancy.[13]

Untreated celiac disease can cause spontaneous abortion (miscarriage), intrauterine growth restriction, small for gestational age, low birthweight and preterm birth. Often reproductive disorders are the only manifestation of undiagnosed celiac disease and most cases are not recognized. Complications or failures of pregnancy cannot be explained simply by malabsorption, but by the autoimmune response elicited by the exposure to gluten, which causes damage to the placenta. The gluten-free diet avoids or reduces the risk of developing reproductive disorders in pregnant women with celiac disease.[14][15] Also, pregnancy can be a trigger for the development of celiac disease in genetically susceptible women who are consuming gluten.[16]

Systemic lupus erythematosus and pregnancy confers an increased rate of fetal death in utero and spontaneous abortion (miscarriage), as well as of neonatal lupus.

Pregnancy does not have an adverse effect on the course of Behçet's disease and may possibly ameliorate its course.[17][18] Still, there is a substantial variability in clinical course between patients and even for different pregnancies in the same patient.[17] Also, the other way around, Behçet's disease confers an increased risk of pregnancy complications, miscarriage and Cesarean section.[18]

Being pregnant decreases the risk of relapse in multiple sclerosis; however, during the first months after delivery the risk increases.[19] Overall, pregnancy does not seem to influence long-term disability.[19] Multiple sclerosis does not increase the risk of congenital abnormality or miscarriage.[20][21]

The effects of depression during pregnancy are difficult to parse from depression before pregnancy as the symptoms of the two overlap. However, the biggest risk factor of depression during pregnancy is a prior history of depression.[22] Most of the research is focused on the consequences of untreated depression regardless if the depression developed during pregnancy or if it was there before conception. Untreated depression has been linked to premature birth, low birth weight, fetal growth restriction, and postnatal complications.[22] On the other hand, however, anti-depressant medications also come with a small risk of pre-term birth, low birth weight, and persistent pulmonary hypertension.[23][22]

In the United States, the prevalence of asthma among pregnant women is between 8.4% and 8.8%.[24] Asthma in pregnant women is strongly associated with multiple adverse health outcomes, including pre-eclampsia, preterm birth, and low birth weight.[25][26] Other conditions such as gestational diabetes, placenta previa, and hemorrhage are inconsistently correlated to asthma.[27] Poorly controlled and severe asthma may exacerbate conditions associated with maternal and neonate morbidity and mortality.[28][29] Asthma treatment recommendations during pregnancy are similar to those in non-pregnant women.[30]