Pregnant and postpartum women with COVID-19 are at risk of blood clotting

Pregnant women who contract COVID-19 may be at higher risk of blood clotting, especially those who become severely ill with the virus, says Associate Professor Sanjaya Senanayake of the Australian National University.

The risk of blood clotting among pregnant women is low overall, but up to five times higher than that for non-pregnant women of the same age, as the body adapts to lessen blood loss during labour and delivery.

Additionally, hypercoagulation has been seen to occur in a large number of severely ill COVID-19 patients, as elements of the virus accumulate in the cells lining the small blood vessels in the lungs, kidney and gut.

“Although COVID-19 is a respiratory illness, it has quickly become apparent to healthcare workers that it has numerous manifestations outside the respiratory system, including causing blood clots,” Senanayake said.

“In some intensive care units, almost half of COVID-19 patients have been getting blood clots, including those that receive anti-clotting prophylactic injections.

“We know that inflammation coming from some infections can affect the clotting cascade in the body. Given that pregnant women already have a heightened risk of clots, getting COVID-19 could present a higher risk, especially with severe disease.

“However, we don’t yet know what that risk might be statistically. At this early stage of the pandemic, we are still just going by small numbers of case reports. It is still a steep learning curve,” he added.

The risk also applies for women who have recently given birth, with the highest risk seen in the first six weeks, postpartum. Some risk may be present for women who have recently experienced pregnancy loss. However, with oestrogen levels often dropping quickly following a miscarriage, the risk may subside earlier than that for a full-term pregnancy.

Additionally, the concerns extend to women on oestrogen-containing birth control pills, with combined oral contraceptives linked, by some reports, to venous thromboembolism — a blood clot typically found in the deep veins of the leg.

As such, the Royal Australian College of General Practitioners (RACGP) recently issued guidelines for women who have been severely ill with COVID-19 to stop taking combined hormonal contraception. Instead, the guidelines recommend a switch to a progesterone-only contraceptive or non-medication methods of contraception.

Despite the fears, Senanayake says that most pregnant women will recover without having to deliver their baby. But until we know more, caution should be taken.

“Like so much with COVID-19, there are still a number of knowledge gaps, so until we know more about the virus, its behaviour in the pregnant population and get some clearer statistics, we need to work with the facts we already have and take reasonable precautions to mitigate the risk,” he concluded.

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