Taking anticoagulant medications during pregnancy can be problematic, but it also might be necessary. Blood clots, which sometimes develop during pregnancy, require treatment with anticoagulants; women with artificial heart valves must take anticoagulants throughout their entire pregnancy. Some anticoagulants carry more risk than others, especially at certain stages of pregnancy.
Types of Therapy
The most common types of anticoagulant therapy are heparin and warfarin. You must take heparin in either subcutaneous injection or intravenously. You take warfarin orally. Both heparin and warfarin decrease the blood's ability to clot. During pregnancy, heparin does not cross the placenta and will not affect the fetus. Warfarin does cross the placenta.
Warfarin Risks
Because warfarin crosses the placenta to the fetus, it can cause birth defects, especially when taken between the sixth and 12th weeks of pregnancy. Fetal warfarin syndrome can include symptoms such as limb deformities, absent kidneys, developmental retardation, eye abnormalities and low birth weight. Miscarriage, stillbirth or intracranial bleeding can also occur. Not all pregnant women who take warfarin have pregnancy or fetal complications. In one group of 418 reported pregnancies in which women took warfarin, 66 percent delivered normal infants, according to the website Drugs.com. Approximately 17 percent ended in miscarriage or stillbirth, and another 17 percent had fetal abnormalities. Toronto researchers who reviewed previous studies of women with prosthetic heart valves who took warfarin throughout pregnancy found an overall risk of fetal damage in 6.4 percent of live births, according to an article published in the January 2000 issue of "Archives of Internal Medicine."
Heparin Risks
Because heparin does not cross the placenta, it does not cause birth defects. But taking heparin can cause bleeding in pregnancy. Heparin use carries a 5 percent to 10 percent chance of bleeding in pregnancy and a 5 percent to 30 percent chance of developing a low platelet count, according to the University of New Mexico. You should not use heparin that contains the preservative benzyl alcohol during pregnancy because the benzyl alcohol can cause gasping syndrome, characterized by respiratory depression, metabolic acidosis and central nervous system depression, according to Drugs.com.
Considerations
If you need to take an anticoagulant during pregnancy because of potentially life-threatening issues and your doctor feels that heparin cannot benefit you, you may need to take warfarin. It's imperative that you are under the care of a perinatal specialist as well as the doctor managing your anticoagulant therapy to understand and control the potential risks and benefits to your baby.
References
- "Archives of Internal Medicine"; Anticoagulation of pregnant women with mechanical heart Valves: A Systematic Review of the Literature; W. Chan, et al.; January 2000
- Drugs: Warfarin
- Drugs: Heparin
- University of New Mexico; Anticoagulation in Pregnancy; May 1998
- March of Dimes; Thrombophilias; July 2009
