Women using hormonal birth control face a very small, increased risk of developing blood clots. Only 1 out of every 1,000 women taking birth control each year develops a clot, which is lower than the risk faced by pregnant and postpartum women, states the National Blood Clot Alliance.
There are several additional factors that raise the risk of developing blood clots while using hormonal birth control: obesity; smoking; being over 35; thrombophilia, which is an abnormality in the body’s coagulation system; being sedentary; and family history of blood clots, according to WebMD.
The type of hormonal birth control used is also a factor. Most hormonal birth control methods combine estrogen and progestin, but there are many varieties of progestin. Recent evidence indicates that methods containing the newest forms of progestin, such as mini pills and the NuvaRing, increase risk more than methods containing older forms of progestin, reports NPR.
Before an individual decides which method is best, she should discuss all the risks and benefits with her doctor, explains WebMD. If there is a family history of blood clots or other risk factors, she may want to consider a progestin-only pill or an IUD. With any type of hormonal birth control, women should familiarize themselves with the signs and symptoms of blood clots.