And even if you were given accurate information back in school, it’s always good to be reminded. (Especially if you’ve tried period sex, thinking you got a free pass… or if you’ve just had a baby and you thinking/hoping there’s a magical grace period.)
Pregnancy during period sex: How it happens
“Yes, it is possible to get pregnant on your period,” confirms Mary Jane Minkin, MD, an OB/GYN at Yale University School of Medicine. She said that while women are more likely to get pregnant during ovulation, there is “always a chance” a person could get pregnant during intercourse.
“This is more likely to occur at the end of your period, due to the length of time that sperm can live inside a woman’s body,” Dr. Minkin tells Motherly.
While it’s not common, it could happen, especially if you have a short cycle.
Generally speaking, a ‘typical’ menstrual cycle is considered anywhere from 24 to 38 days, with an ovulation window around day 13 to 15; right in the middle of the cycle.
But if you have a short cycle, ranging from 21 to 23 days, you’re more likely to ovulate earlier in the cycle, which could be right after your period ends.
Because sperm can survive in your vagina for up to 5 days, if you have sex toward the end of your period and then ovulate 4 or 5 days later, you could end up getting pregnant.
While the risk is low, it’s not zero. To get a more precise predicition of when you’re ovulating, try tracking your cycle through an app or ovulation tracking device. Any tracking method will be more accurate the longer you use it and enter data.
Fertility and age
Dr. Minkin points out that younger women (from their late teens until about 35) have overall higher fertility, so they’ll have a higher chance of conceiving in general.
But that doesn’t mean that the over-35 crowd can’t have a surprise if they have sex while menstruating. “An older woman may be having some issues with not ovulating as regularly as she used to—so it is possible that she might ovulate a bit earlier—setting her up for inadvertently getting pregnant,” Dr. Minkin notes.
Bottom line: If you don’t want to conceive, always use contraception. Even if you have sex at the end of your period, try a barrier method of birth control if you aren’t using a long-acting method.
Normalizing period sex
Period sex used to be a taboo topic, but it’s become more normalized in recent years. While it’s maybe not for everyone, some women say it can ease cramps and be especially enjoyable (extra lubrication!).
Van Eijk AM, et al. Menstrual cup use, leakage, acceptability, safety, and availability: a systematic review and meta-analysis. The Lancet Public Health. DOI: 10.1016/S2468-2667(19)30111-2
Verma P, et al. Pregnancy risk during menstrual cycle: misconceptions among urban men in India. Reproductive Health. DOI: 10.1186/s12978-017-0332-3
U.S. Centers for Disease Control and Prevention. The Lowdown on How to Prevent STDs.