Think you can't get pregnant during your period? Think again. Guest authors Dr. Aaron E. Carroll and Dr. Rachel C. Vreeman put the myth to rest in an excerpt from their new book Don't Put That in There!: And 69 Other Sex Myths Debunked.
Myth: You can’t get pregnant during your period
For most women, the chance of getting pregnant during your period is much less than at other times of the month. But it is never, ever impossible. Any time you hear someone say “You can’t get pregnant if…” you should think to yourself that someone is kidding themselves. If there is even a remote chance that a sperm and an egg are coming in contact with each other, then you can have a pregnancy.
It is much less likely that you will get pregnant during your period than during the time of the month a little before your period when your body sends an egg out, also known as the time when you are ovulating. Even though it is much less likely, it is still possible. The usual pattern of things is that a woman’s body releases an egg, which travels through the fallopian tubes, which is where it would need to be fertilized by a sperm if she is going to become pregnant, and then the egg moves into her uterus and disintegrates if it has not been fertilized. Ovulation or the release of the egg usually happens 2 weeks before she starts her period. This is the time when pregnancy is most likely to occur.
If you have short menstrual cycles or irregular periods, there is a greater chance that you might have an egg present during the time that you are having a period. A woman’s egg can live for several days, and not all women ovulate two weeks before their period. Some ovulate much closer to the time that the period occurs. Plus, sperm can live for days, even up to a week, in the nice, wet environment inside a woman’s body. So, the combination of the egg being around and the sperm being around could lead to a pregnancy, even if the timing is unusual.
Some people attempt to use the “rhythm method” to prevent pregnancy. In other words, they only have sex during the “safe” days of pregnancy, when the woman is least likely to have an egg around. If you have really regular periods, you keep track of them carefully, and you can estimate the time when you ovulate by changes in the thickness of cervical mucus or body temperature, you might have a slightly better chance to avoid pregnancy for a while.
The “rhythm method” teaches us that no time is completely “safe” for avoiding pregnancy. Even when you are really careful about only having sex at “safe” times, the rhythm method is not a very effective method for preventing pregnancy. Timing your sex leads to pregnancies more often than using birth control pills, condoms, or injectable hormones. If you have sex without any of these other kinds of birth control, there is really no safe time to have sex.
If you don’t want to get pregnant, use real birth control. And if you don’t want to get a sexually transmitted disease, you need to use a condom.
. . .
Dr. Aaron E. Carroll is professor of pediatrics at Indiana University’s School of Medicine and director of the Center for Health Policy & Professionalism Research and the Center for Pediatric and Adolescent Comparative Effectiveness Research. Dr. Rachel C. Vreeman is an associate professor of pediatrics at Indiana University School of Medicine and codirector of Pediatric Research for the Academic Model Providing Access to Healthcare (AMPATH) in Kenya.