The basics
Can you get pregnant on your period?
Yes, it is possible, though less likely than at other times in your cycle. Sperm can survive inside the body for about 3 days, sometimes up to 5, and you can become pregnant from sex from 5 days before ovulation until 1 day after. In a short cycle, ovulation can come soon after your period ends.
How does the fertile window work?
ACOG explains that an egg can survive for about 24 hours after ovulation, and sperm for about 3 days, sometimes up to 5. Pregnancy is possible from sex anywhere from 5 days before ovulation to 1 day after it. Chances are highest when live sperm are already in the fallopian tubes when ovulation happens.
Why can it be possible on a period?
Ovulation moves around from cycle to cycle, even for people with regular periods. In a short cycle it can come soon after the bleeding stops. And bleeding in the middle of a cycle can be mistaken for a period. So the safe days are not as predictable as they sound.
Is a period a reliable form of birth control?
No. Counting days is not a reliable way to avoid pregnancy. The NHS puts natural family planning at about 76% effective with typical use. Condoms are 82% effective with typical use, and the implant and coils are over 99%.
Do I need protection from infections too?
Yes. Condoms are the only method that protects against both pregnancy and sexually transmitted infections. This is true during a period too.
Frequently asked questions
What if I had unprotected sex during my period?
Emergency contraception can prevent pregnancy if used within 3 to 5 days, and the sooner the better. A pharmacy, doctor or sexual health clinic can help.
Can I get pregnant right after my period ends?
It can happen, especially with short cycles, because sperm can survive for several days.
Does a period mean I’m not pregnant?
A bleed at the time of your period doesn’t always mean you aren’t pregnant. If you have other signs, take a test.
Sources
Seventh is a free period and cycle tracker for iPhone and iPad, by doogud. This article is general information, not medical advice. If something feels wrong, see a doctor.
