Women's Health

IVF pregnancies may increase risk of blood clots, blocked arteries

  • IVF treatment.

    IVF treatment.

For couples struggling to get pregnant, in vitro fertilization (IVF) is a relatively safe medical procedure that can help them overcome infertility.  However, the procedure may come with a slight associated risk: blood clots and blockages.

New research from the Karolinska Institute in Sweden found women who became pregnant through IVF are at increased risk for pulmonary embolisms – a blockage of a major artery in the lung – and venous thromboembolism (blood clots) during the first trimester of pregnancy.

In vitro fertilization is a process that involves fertilizing an egg with a sperm outside the body and then implanting the resulting embryo back inside the mother’s womb.  Since the first IVF baby was born in 1978, more than 5 million babies have been conceived and born through the procedure.

According to the researchers, previous studies have found IVF to be just as safe as normal pregnancies, but they weren’t necessarily convinced the two methods were on par with one another.

“I didn’t believe that because when you do IVF procedure…you have to stimulate the follicles of the ovaries to get the eggs to harvest,” Peter Henriksson, a professor and chief physician at the Karolinska Institute, as well as the study’s lead author, told FoxNews.com.   “The estrogen levels increase, and high estrogen levels are linked with increased propensity of blood to coagulate.”

An increased risk of thrombosis is already a well-established side effect of normal pregnancies, occurring in one to two out of every 1,000 pregnancies.  However, blood clotting has been reported with more frequency in IVF pregnancies, but no previous research has established an increased risk.

To determine the incidence of blockages and blood clots during pregnancy, Henriksson and his colleagues analyzed information from 23,498 women who had undergone IVF, comparing them to 116,960 women who had normal pregnancies.  The average age of the patients was 33 for both groups.

Through the use of public health records, the researchers determined how many of the women had been diagnosed with pulmonary embolism (PE) and venous thromboembolism (VTE) during their first trimester.  Of the women who had done IVF, 4.2 out of 1,000 were diagnosed with VTE, compared to only 2.5 out of 1,000 those who had normal pregnancies.

The increased risk also held true for PE, with .08 percent of the IVF women suffering from a blocked artery, compared to only .05 percent of the women unexposed to IVF.

While the numbers may seem small, the risk of blood clots is significant.  Currently PE is the leading cause of maternal deaths.

“If a part of that blood clot breaks, circulation will carry that blood clot to the right side of the heart and further on to the pulmonary artery,” Henriksson explained. “And in the pulmonary artery, the blood clot could hinder circulation.  If the clot is great or there are repeated emboli (blockage), then it could completely block circulation, and that is…potentially very dangerous.”

With any major health problem, early detection is always crucial, and Henriksson hopes this research will spark further investigation into the matter – as well as help educate physicians and women alike about the risks of IVF.

“I hope that women will have an increased suspicion if they get symptoms of breathlessness, or physicians could suspect this has to do with pulmonary thrombosis, and then women get the correct diagnosis before it’s too late.”

The study was published online in the British Medical Journal.