National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Hereditary antithrombin deficiency

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I have two clotting disorders, antithrombin 3 deficiency and MTHFR. I also only have one kidney. My question is what are all my risks and do the risks outweigh the benefits for getting pregnant? We want to have children, but are scared with everything going on. Thank you!

The following information may help to address your question:


What pregnancy risks are associated with hereditary antithrombin deficiency, MTHFR gene mutation, and solitary kidney?

Most women with antithrombin deficiency have successful pregnancy outcomes, however studies have shown that they are at an increased (31-49%) risk for blood clots during and following pregnancy.[1] They are also slightly more likely to suffer pregnancy loss without treatment than women without the deficiency (risk for pregnancy loss is around 19%, in comparison women without the deficiency have a 12% risk).[2][1] Having a single MTHFR gene mutation is not associated with significant increased pregnancy risks,[3] however having two MTHFR gene mutations, or having combined genetic risk factors (e.g., MTHFR and antithrombin deficiency) may add to overall risk. Unfortunately it is very difficult to calculate these specific risks. For women with inherited thrombophilias (like antithrombin deficiency), many recommend the use of low molecular weight or unfractionated heparin during pregnancy and for at least six weeks following delivery to manage clot risks.[9441][3]

The advocacy and support group, Clot Connect summarizes the treatment guidelines for pregnant women with thrombophilia at the following link:

Pregnancy and Blood Clots: Prevention, Diagnosis, Treatment (Clot Connect)

Solitary kidney may occur as a result of kidney donation, medical treatment, or due to a congenital birth defect. Having solitary kidney as a result of kidney donation is associated with an increased risk for high blood pressure (preeclampsia) during pregnancy, but maternal and fetal outcomes are comparable to women with two kidneys.[4] It is not clear if and if so how preeclampsia risk might complicate thrombophilia related risks. Risks for pregnancy complications in women with a history of medical treatment resulting in solitary kidney or congenital absence of one kidney will vary from case to case. Women who are born with a single kidney should be evaluated for anatomical differences of their internal reproductive tract. Around 30% of women born with a single kidney have abnormalities of the reproductive tract, the presence of which may affect fertility and pregnancy outcomes.[5][4]

Further information on solitary kidney is available at the following Web site:

Solitary Kidney (Kidney & Urology Foundation of America, Inc)
Last updated: 9/1/2015

Who should I talk to regarding my pregnancy risks?

We strongly recommend that you talk to your doctor regarding a referral to a Maternal Fetal Medicine (MFM) specialist. MFM doctors are high-risk pregnancy experts, and are often involved in the care of women with thrombophilias and other medical conditions. The Society for Maternal-Fetal Medicine offers the following tool for finding MFMs in your area:

Find an MFM Specialist (Society for Maternal-Fetal Medicine)

The following support groups are a source for further information and support:

Clot Connect
Campus Box 7305
Mary Ellen Jones Bldg, Room 318
116 Manning Dr.
Chapel Hill, NC 27599
Telephone: 919-966-2809
E-mail: http://www.clotconnect.org/about-clot-connect/contact-u
Website: http://www.clotconnect.org

National Blood Clot Alliance
110 North Washington Street
Suite 328
Rockville, MD 20850
Toll-free: 877-466-2568
Telephone: 301-825-9587
E-mail: info@stoptheclot.org
Website: http://stoptheclot.org

Sidelines High Risk Pregnancy Support
P. O. Box 1808
Laguna Beach, CA 92652
Toll-free: (888)447-4754 (HI-RISK4)
E-mail: sidelines@sidelines.org
Website: http://www.sidelines.org
Last updated: 9/1/2015

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

Warm regards,
GARD Information Specialist

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  1. Patnaik M, Moll S. Inherited antithrombin deficiency: a review. Haemophilia. 2008; 14:1229–12. Accessed 9/1/2015.
  2. Bauer, Kenneth. Antithrombin Deficiency. National Organization for Rare Disorders (NORD). 2015; http://rarediseases.org/rare-diseases/antithrombin-deficiency/. Accessed 8/5/2015.
  3. Lockwood CJ. Inherited thrombophilias in pregnant patients: detection and treatment paradigm. Obstet Gynecol. 2002 Feb; 99(2):333-41. Accessed 9/1/2015.
  4. Neelu M et al.,. Pregnancy induced hypertension with unilateral renal agenesis. J Obstet Gynecol India. January/February 2005; 55(1):77-78. http://medind.nic.in/jaq/t05/i1/jaqt05i1p77.pdf. Accessed 9/1/2015.
  5. Heinonen PK. Gestational hypertension and preeclampsia associated with unilateral renal agenesis in women with uterine malformations. Eur J Obstet Gynecol Reprod Biol. 2004 May 10; 114(1):39-43. Accessed 9/1/2015.
  6. Lipe B, Ornstein L. Deficiencies of Natural Anticoagulants, Protein C, Protein S, and Antithrombin. Circulation. 2011; http://circ.ahajournals.org/content/124/14/e365.full. Accessed 3/6/2011.
  7. Ilonczai P et al.,. Management and outcome of pregnancies in women with antithrombin deficiency: a single-center experience and review of literature. Blood Coagul Fibrinolysis. 2015 Jul 29; Accessed 9/1/2015.
  8. Khalafallah AA et al.,. Review of Management and Outcomes in Women with Thrombophilia Risk during Pregnancy at a Single Institution. ISRN Obstet Gynecol. 2014 Feb 17; 2014:381826. Accessed 9/1/2015.