They say you can't get pregnant during your period…

It is one of the most widespread misconceptions in women's health: during your period, you are safe. The reality is more nuanced, and this belief lies behind pregnancies that nobody had planned.

What the science says

This is false. The risk is low at the start of a period, but it is never zero. Two mechanisms explain why.

Sperm survive for several days. In the female genital tract, they can stay alive for about five days. Sex is therefore not "fertile" only on the day of ovulation: it can be fertile several days before. Studies that followed women cycle after cycle show that the fertile window covers the five days before ovulation, plus the day of ovulation itself.

Ovulation does not always happen in the middle of the cycle. Counting the first day of your period as day 1, a woman with a short cycle of 21 to 24 days ovulates around day 7 to 10. If her period lasts six or seven days, sex at the end of her period already falls within the fertile window.

There is one more detail: some bleeding outside the period, such as mid-cycle spotting, is sometimes mistaken for a period when ovulation is approaching.

Why it matters

This misconception leads to unprotected sex that people believed carried no risk, and therefore to unintended pregnancies or to the use of emergency contraception. It also makes people forget something essential: a period does not protect against sexually transmitted infections. The condom remains the reference protection.

What to remember

If you do not want to become pregnant, a contraceptive method suited to your situation is the best protection, and condoms also protect against infections. After unprotected sex, emergency contraception exists: it is available from pharmacies, and it works better the sooner it is taken.

Unsure which contraception to choose? It is a subject we can discuss together during a consultation.