Women Urged Not to Scrap Birth Control After AstraZeneca Blood Clot Comparisons

Concerns have been raised of a contraceptive pill "scare" after the blood clot risks of birth control medication were widely compared with that of the AstraZeneca (AZ) COVID vaccine.

This week, Newsweek and others reported the small risk of blood clotting incidents when using contraceptives appeared to be higher than the even smaller risk currently associated with the AZ shot.

It was also pointed out that other everyday activities, such as smoking, long-haul flights, and even having COVID, all increased the risk of having a blood clot.

On Thursday, the British Pregnancy Advisory Service (BPAS) issued a statement voicing concern about the way contraceptives had been compared to the AZ jab, and stressed the benefits of contraceptive pills outweigh the risks of serious side effects, such as the blood clot type known as VTE.

They also said they feared a repeat of the 1995 "pill scare," which led to a significant increase in unplanned pregnancies.

BPAS said: "Rightly reassuring the public about the safety of the AstraZeneca vaccine must not come at the expense of trust in the most commonly used contraceptive method in the UK.

"Combined hormonal contraceptives are overall very safe for most women to take—the very small increased risk of venous thrombosis (VTE) with use of the combined pill is far lower than the risk for VTE during or after pregnancy.

"We advise that any woman who is concerned about their current method of contraception seeks advice from their GP before discontinuing. An unplanned pregnancy presents a greater risk of VTE than the use of the combined hormonal contraception."

The risk of blood clots in women taking contraceptive pills has been variously reported as 1 in 1,000 and 5 in 10,000.

Comparisons of blood clot risks between the AZ vaccine and other things were drawn this week after the European Medicines Agency (EMA) said that blood clots with low blood platelets should be listed as very rare side effects of that vaccine.

The decision was based on a review of 86 cases of blood clot incidents that had shown up in vaccine side effect reporting systems in the EU and the UK, where around 25 million people have had the AZ vaccine.

On Wednesday, the UK's MHRA medicines regulation agency said the blood clotting incidents after taking the AZ vaccine were "extremely rare" and that according to data as of March 31, the overall risk was about four people in a million.

As BPAS pointed out, pregnancy itself is considered to be a risk factor for blood clots. The U.S. Centers for Disease Control and Prevention (CDC) states that women are five times more likely to experience a blood clot if they are pregnant than if they are not.

This is because of natural bodily changes. A woman's blood clots more easily during pregnancy in order to lessen the amount of blood that is lost during delivery. In addition, the pressure of the growing baby on the woman's pelvis may limit blood flow to certain areas, increasing blood clot risk. Official CDC advice on blood clots and pregnancy is available here.

Woman holding birth control pills
A stock image shows a woman holding a pack of birth control pills. A birth control group has said comparisons to the AZ vaccine should not come at the expense of trust in the pill. Rattankun Thongbun/iStock