Pregnant women have enough to worry about. But research shows that blood clots from COVID-19 may not be one of them.

Blood clots that seal a cut or wound are welcome and necessary; clots inside your body are not. To keep your organs and body tissues healthy, fresh blood must pump through the blood vessels and “used” blood must return to the lungs to be refreshed with oxygen. Blood clots cause two serious problems: they either block or restrict the blood flow, which is dangerous, or break off and travel to other parts of the body, which can kill you. In the first event, body tissue can die from lack of nutrients because the blood can’t flow freely, leading to gangrene. In the second event, the broken off pieces can lead to vital organs like the heart, the lungs and the brain, heart attacks, pulmonary emboli, or strokes.

Pregnancy Affects Clotting

Pregnant women have a higher risk of these clots than women who aren’t pregnant. But COVID-19 seems to have given them a pass — one of the few, if only, groups shown such compassion. 

First, an explanation on why pregnant women are at risk for blood clots. When a woman gets pregnant, her body begins to prepare for delivery in several ways; two increase the blood clotting risk.

First, the blood “thickens” a bit during pregnancy to lessen the amount of blood lost during delivery. Otherwise, it would be hard to stop the bleeding that occurs when the placenta separates from the uterus. Second, carrying the baby can also contribute to clots. As the baby grows, it may press down on the blood vessels in the mother’s pelvis, restricting how much blood can flow back and forth from her legs. Finally, after pregnancy, women are still at risk for a few months, particularly if they had a Caesarian section or have to remain on bedrest.




Pregnant women can also fit into other high risk groups along with, such as those who:


  • Are on prolonged bed rest or are immobile
  • Have a blood clotting disorder
  • Smoke
  • Are overweight or obese

Women Who Take Estrogen Are Also at Risk

The researchers also looked at women who use oral contraceptives to prevent pregnancy or hormone replacement therapy (HRT). The Centers for Disease Control and Prevention says that 12.9% of women in the U.S. who use contraception use the birth control pill. In addition, thousands of women take HRT after menopause, as do transgender women. They, too, are at higher risk of developing blood clots, because of the estrogen in the medications. Their risk can climb if they belong to any of the risk groups listed above, in addition to being over 60 years old. “Estrogen, a key ingredient in most birth control pills, increases a woman’s risk for developing a blood clot by increasing the plasma concentration of clotting factors,” Susan Todd Peeler, MD, a board certified gynecologist with The Institute for Gynecologic Care at Annapolis, told Medical Daily. “This shifts the balance towards [clot] formation and prevention of clot breakdown.” She added that the clotting effects from the birth control medications depend on the amount of estrogen as well as the type of progesterone the pill contains.

Now to COVID-19

Physicians and researchers are learning more about COVID-19 as they treat more patients. One important and potentially fatal complication associated with the infection is blood clots. According to an article published by The Ohio State University Wexner Medical Center, physicians found clots in the brain, heart, lungs, and legs in many of their COVID-19 patients. Notably, Broadway star Nick Cordero, who died from COVID-19, developed blood clots earlier in his fight, which forced his physicians to amputate one leg. Given that these pregnant women and those taking estrogen are already at higher risk, researchers wondered if that risk was amplified if they became infected with COVID-19. And if so, what would be the best way to treat them?

“During this pandemic, we need additional research to determine if women who become infected with the coronavirus during pregnancy should receive anticoagulation therapy or if women taking birth control pills or hormone replacement therapy should discontinue them,” said one of the study’s authors, Daniel I. Spratt, MD, in a press release issued by the Endocrine Society. Spratt is from the Maine Medical Center in Portland, and Tufts University School of Medicine in Boston. “Research that helps us understand how the coronavirus causes blood clots may also provide us with new knowledge regarding how blood clots form in other settings and how to prevent them.”

The authors wrote that there are many uncertainties but so far, there has not been an increase in pregnant women getting blood clots if they also had COVID-19, but researchers have detected some abnormalities in the placenta.

What Does This Mean in Real Life?

Peeler was not surprised to hear that there was a concern that pregnant women or those using hormones may be at increased risk of clots. However, she doesn’t recommend anticoagulants (blood thinners) be started or oral contraceptives/HRT be stopped as a matter of course. “There is incomplete evidence to support discontinuation of estrogen therapy (HRT or OCP) in these patients,” she said. “However, the patient should discuss all medications with their treating physician at the time of COVID-19 diagnosis for personalized advice.” Adults who are hospitalized with COVID-19 should be watched and treated for blood clots as would any other hospitalized adult, she added. “Any medication that potentially increases the risk for a blood clot would be discontinued in these patient’s upon admission. For pregnant patients admitted to the hospital with COVID-19, recommendations for [clot prevention] are the same as those for hospitalized nonpregnant patients.”

If you are pregnant, or you take birth control pills or HRT, speak with your doctor about what you should do if you are exposed to COVID-19 or if you have symptoms. Because this illness is so new, there are still many unknowns and speaking directly with a healthcare professional who knows your situation is the best step.