The reason expectant women should be mindful of the link between pregnancy and DVT is that an untreated clot has the potential to break free and travel through the bloodstream. “The fear is it will move to the heart or lungs and cause a pulmonary embolism, which can lead to death,” says Daniel Roshan, MD, a maternal fetal medicine specialist and an assistant professor of obstetrics and gynecology at the NYU Grossman School of Medicine in New York City.
Causes of Deep Vein Thrombosis in Pregnancy
Why is there an increased risk of deep vein thrombosis when a woman is expecting? “A lot of physiological changes take place during pregnancy,” says Pamela Berens, MD, a professor of obstetrics and gynecology with McGovern Medical School at UTHealth in Houston. One is the compression in the pelvis from the baby. “There are also changes in clotting factors in the blood that begin early in pregnancy and last until a woman is six weeks postpartum,” she added. Pregnancy hormones play a role. “There’s a lot of estrogen circulating during pregnancy, and estrogen increases the risk of blood clots,” Dr. Roshan says. Women on birth control pills that contain estrogen are at a similar increased risk of DVT. Roshan says that women with genetic clotting disorders, called thrombophilias, are at an even higher risk for deep vein thrombosis in pregnancy.
Risk Factors for Deep Vein Thrombosis in Pregnancy
Certain factors that can further raise your chances of developing deep vein thrombosis in pregnancy include:
Being 35 or olderPrevious blood clot during pregnancy or clot outside of pregnancyA genetic predisposition to blood clotsMultiple birthsBeing overweightSmokingFertility treatments involving use of hormonesProlonged immobility, such as bed rest, travel, or recovery after deliveryCertain pregnancy-related complications like preeclampsia or conditions like diabetes.
Having a cesarean delivery (C-section) nearly doubles a pregnant woman’s risk of a dangerous blood clot, the CDC reports. Race can also be a risk factor. Research has shown that the overall incidence of DVT and pulmonary embolism is 30 to 60 percent higher in Black people than in white people. This accounts for both men and women. Significant racial disparities exist in heart-related complications, including blood clots, among pregnant and postpartum women in the United States. According to a study published in the Journal of the American Heart Association in December 2020, pregnant Black women were found to have a 42 percent higher likelihood of developing a blood clot in the lungs compared with white women. Black women also had a higher incidence of heart attack, stroke, and heart muscle weakness and were also more likely to die in the hospital.
How to Recognize DVT Symptoms in Pregnancy
You have enough on your mind without stressing over deep vein thrombosis. So instead of worrying, be aware of the symptoms. Most blood clots during pregnancy occur in the legs. “So watch for tenderness in the calf and thighs, pain in the back of your calf, and swelling, particularly if it is on one side more than the other,” Roshan said. Blood clots during pregnancy that have moved to the heart or lungs can cause chest pain, shortness of breath, or both. This signals an even more serious situation. “If you have any signs of DVT, seek medical attention right away,” Roshan said. A healthcare professional will be able to easily see if your discomfort is due to a pregnancy blood clot by performing an ultrasound of the affected area. If you indeed have DVT, the treatment will be a blood thinner, usually Lovenox (enoxaparin), which is safe during pregnancy. “We treat the clot with a therapeutic dose for a few months and then lower it to a prophylactic (preventive) dose,” he said. For pregnant women with a prior history of DVT or blood clots during pregnancy or with a genetic thrombophilia, doctors usually prescribe blood thinners in the lower preventive dose. “We usually monitor women taking blood thinners throughout their pregnancies because as the pregnancy progresses, they sometimes need higher doses,” Roshan said. “And for women with a family history of DVT but no personal past history, we sometimes prescribe baby aspirin and tell them to be particularly cautious about symptoms.”
Prevent Pregnancy Blood Clots
By virtue of being pregnant or in the postpartum period, expectant women and new moms are at an increased risk of DVT, so you can’t eliminate the risk completely. But there are some steps you can take to reduce your risk of blood clots. Keep moving. “If you are overweight and sedentary, that will affect your blood flow and increase your risk for deep vein thrombosis in pregnancy,” Dr. Berens says. “So stay active and maintain a healthy weight.” If you have to be on bed rest because of an injury or complication in your pregnancy, your doctor may prescribe blood thinners as a precautionary measure. Get up during travel. “Flying in itself is a risk factor for DVT, so pregnant women who fly are definitely at an increased risk,” Berens said. If you have to fly, get up and move around every hour or two and do ankle roll exercises while you sit. “And do the same thing if you go on a long car or bus ride,” she added. Wear compression stockings. Because they help improve circulation and reduce swelling in the legs, compression stockings can help lower your risk of deep vein thrombosis in pregnancy, Roshan said. Drink lots of water. Staying hydrated during pregnancy helps prevent clots by keeping the blood from getting too thick, Roshan said. The CDC recommends that women drink 10 glasses of liquid every day during pregnancy and 12 to 13 glasses every day while breastfeeding. Overall, err on the side of caution when it comes to blood clots during pregnancy, for your sake and the sake of your baby. “Deep vein thrombosis in pregnancy can be life-threatening, so if you see any signs, don’t hesitate to go to your doctor to get checked,” Roshan said.
