You may have heard that if you have sex while you're on your period you can't get pregnant, but is that a fact or an old wives tale?
The truth is you definitely can become pregnant when you have your period, but it's much less likely. Women who prefer not to use more reliable methods of birth control such as oral contraceptives, IUDs, or condoms may use what's commonly called the “rhythm method” to avoid becoming pregnant. In a nutshell, the rhythm method involves tracking your cycle throughout the month and avoiding intercourse during ovulation (when a woman is fertile, or most likely to become pregnant). Since menstruation is the process of shedding the unfertilized egg after ovulation has occurred, most women won't become pregnant during their periods.
However, there's a catch.
Sperm can live inside the body for up to five days, so it's quite possible to have sex during the later days of period and then become pregnant a few days later when ovulation begins. It's also important to keep in mind that just as some women have irregular periods, ovulation doesn't always happen when it's supposed to. Therefore you may ovulate earlier or later than you expect. Sometimes women with irregular periods may even mistake heavy spotting for a period, since their menstrual cycle is not predictable. So while the rhythm method may work fine for some women, others won't be so lucky.
If you wish to use the rhythm method as your only form of birth control, it's important to keep very close track of your cycle, preferably using a period tracker app or at least a calendar or monthly planner. Don't just rely on the appearance of your period – make sure your ovulation cycle is over before having vaginal intercourse. If you have irregular periods, having sex on your period will be a less effective way to prevent pregnancy. So while some women choose not to use other methods of birth control for religious or health reasons, if possible a backup method is recommended.
It's important to remember too that while having sex on your period may prevent pregnancy, it will not protect you or your partner from sexually transmitted diseases (STDs) or infections (STIs). Herpes, HIV and AIDS as well as bacterial and fungal infections can all be spread through direct contact during intercourse. In fact if you're having vaginal intercourse during your period, you may be more likely to spread or get and STD or STI, so always make sure both you and your partner are in good sexual health before having unprotected sex.
So can you get pregnant during your period? Yes, but it's unlikely. However, a potential pregnancy isn't something to leave up to chance, so if you do choose – for whatever reason – to prevent pregnancy by using the rhythm method and having intercourse during your period, use an app like Clue (http://www.helloclue.com/) to keep track of your ovulation cycles and limit the possibility of human error.