How are blood clots treated during pregnancy?

Blood clots are treated the same way during pregnancy as they would be outside of pregnancy, except that warfarin is rarely used. Whether women are treated initially with standard “unfractionated” heparin or LMWH, they will ultimately need to receive twice-daily injections of an anticoagulant until after delivery of the baby. Women are sometimes concerned about having to give their injections into their abdomens while they are pregnant. In fact, the needle is very short and never goes below the fatty layer of tissue under the skin.

Special plans may need to be made around the time of delivery or miscarriage in a woman with a blood clotting problem. LMWH, if it is in the mother’s system at the time of miscarriage or childbirth, or when an epidural or spinal anesthetic is desired, may increase the risk of bleeding complications. Therefore, standard or “unfractionated” heparin, which is shorter acting, may be used during the last few weeks of pregnancy and held at the time of delivery. Alternatively, LMWH may be continued and withheld in anticipation of delivery or surgery for miscarriage. LMWH can be resumed after delivery. One or two weeks after delivery, when the risk of major bleeding has subsided, women can be converted to warfarin for the remainder of their treatment.