Blood clotting risk quickly drops after stopping hormonal contraceptives

Using birth control pills and other hormone-based contraceptives is known to elevate the risk of blood clots about three-fold, but a new study suggests that this risk largely goes away within two to four weeks after one stops using these contraceptives, according to recent research.

For the study, researchers collected blood samples from 66 women on hormone-based birth control at six timepoints before and after the women stopped using their contraceptives. Participants voluntarily stopped using hormonal contraceptives for personal reasons. Dr. Blondon and team then compared the samples with blood from a control group of 28 women who were not using hormone-based birth control.

The researchers measured several biomarkers that are associated with combined hormonal contraceptives and clotting activity. These include global markers of coagulation activation due to hormones and individual coagulation factors (factor VIII and factors that inhibit clotting)

As expected, participants showed elevated levels of clotting markers before they stopped using their contraceptives. However, these coagulation markers dropped precipitously within one to two weeks after they stopped taking birth control, and by week 12, all markers were similar to the control group.

Overall, around 80% of the total drop in clotting markers seen in these women occurred within two weeks of stopping their birth control and 85% of the drop occurred within four weeks. This suggests that the likelihood of developing clots due to birth control returns to nearly normal levels within the first few weeks of stopping birth control.

Ref: AMERICAN SOCIETY OF HEMATOLOGY JOURNAL Blood