blood clot and pregnancyThe overall risk of having blood clots during pregnancy is extremely low with just 1 in 1,000 pregnancies being affected. According to a recent study published in BMJ, women who conceive with the help of IVF are more likely to suffer blood blots than women who conceive naturally.

The study collected data from nearly 24,000 women who conceived after IVF and compared that data with data collected from about 117,000 women who conceived naturally. The rate of blood clots in the IVF population was 4.2 per 1,000 compared to 2.5 per 1,000 in the natural conception group. When researchers compared risk by trimester, women in the IVF group had a higher risk of blood clots with 1.5 cases per 1,000 pregnancies compared to 0.5 cases per 1,000 pregnancies with natural conception.

According to the study, women who undergo IVF a risk four times higher for developing venous thrombosis and seven times higher for developing pulmonary embolism when compared to women who conceived naturally. While the risk gap closed significantly as the pregnancies progressed, the IVF group consistently held the higher risk factor.

Venous thrombosis is a condition where blood clots can develop in the veins. Deep vein thrombosis, one type of venous thrombosis, can lead to pulmonary embolism. Pulmonary embolism occurs when a blood clot blocks the main artery in the lung. Pulmonary embolism can lead to sudden death.

Doctors involved with the study believe women should be made aware of the increased risk of pregnancy blood clots that come with IVF treatments. If blood clots are diagnosed, pregnant women can be treated with blood thinners to reduce health risk to the pregnant woman and fetus.

Source: Peter Henriksson, Eli Westerlund PhD, Håkan Wallén, Lena Brandt, Outi Hovatta, Anders Ekbom. Incidence of pulmonary and venous thromboembolism in pregnancies after in vitro fertilisation: cross sectional study. BMJ 2013; 346 doi: