Pregnancy and Childbirth
Pregnancy is a major risk factor for the development of dangerous blood clots. Women who are pregnant or who have just given birth are at increased risk for blood clots. Pregnancy does not directly cause blood clots, but it does pose a four-fold increased risk for the development of a blood clot. That risk actually increases to about 20-fold in the weeks immediately following childbirth, and is at its highest — a risk of 100-fold — in the first week after the baby is born.
This tendency for a woman’s body to form clots during pregnancy is the result of a natural biological response intended to protect women against the potentially major bleeding challenges of miscarriage and childbirth.
What’s Your Risk?
Women should look into whether or not there is a history of blood clots in their family, and also recognize some of the other major risk factors for blood clots, including: hospitalization, surgery, trauma, obesity, smoking, and immobility.
How Can You Reduce Your Risk?
Women should discuss their potential risk factors with their doctors, and make sure that they take steps to address any risks they might identify.
In general, there are three groups of women who need to be take anticoagulation or blood thinning medication during pregnancy:
After delivery, women who have not had a clot, but do have major risk factors, may need to take anticoagulation for a short period of time.
Prevent Blood Clots
Know the Signs and Symptoms, Be Your Own Advocate
Understand the symptoms of blood clots and pay attention to your body for signs of a problem.
Work with your doctor to make sure you reduce your blood clot risk during pregnancy.
Do you have a history of blood clots or an inherited or acquired blood clotting disorder?
There’s more information you may need:
Anticoagulation Therapy While Pregnant
While oral anticoagulants, or blood thinners, such as warfarin, dabigatran, rivaroxaban and apixaban are most commonly prescribed, they are not considered safe for unborn babies. Women who take blood thinners should contact their doctor immediately upon finding out they are pregnant. Your doctor may recommend that you switch from blood thinning pills to blood thinning medications that are injected under the skin, such as standard or unfractionated heparin and also low-molecular-weight heparin (LMWH), because they do not cross the placenta or enter the bloodstream of the unborn baby and are safe to use during pregnancy. LMWH is preferred over heparin because it presents fewer side effects. Women can rest assured that injections are not dangerous to the fetus, even though they are given in the abdomen, because the needles are very small and do not reach beyond the fatty layers of stomach tissue just beneath the skin. Heparin and LMWH have been used in pregnancy by thousands of women with no birth defects or bleeding problems in their unborn babies.
Women who are on blood thinners require special consideration when it comes to labor and delivery, but a successful delivery is entirely possible. Women may or may not be converted to standard heparin, which is shorter-acting than LMWH, a few weeks ahead of delivery. LMWH or heparin can be held a few hours prior to delivery to further reduce the risk of bleeding and allow for the use of an epidural. Pneumatic compression devices, or simple sleeves with air pumps that inflate and deflate the sleeves, also may be placed on your legs and/or arms to help improve blood flow during labor and delivery.
Giving Birth While Taking Blood Thinners
Risk Management After Giving Birth
Women are at their highest risk of a blood clot in the six weeks following the baby’s birth.
After delivery, women with clotting disorders need to resume anticoagulation or blood thinner therapy. Women need to continue taking anticoagulants for at least six weeks post-delivery, either injections or an oral anticoagulant, as the risk for bleeding is reduced, to protect themselves from blood clots. The duration of anticoagulation after six weeks post-delivery will depend on a woman’s individual clotting risks.
Women can breastfeed while on LMWH injections or warfarin, but the safety of newer oral anticoagulants as it pertains to breastfeeding has not yet been determined.