Having Sex during your period can lead to pregnancy.

You are probably here because you had unprotected sex while you were still having your period. You thought it was a “safe” time, but now you are concerned about the possibility of getting pregnant. While can get pregnant at that time, it isn’t likely. It all depends on how your cycle works.

How You Get Pregnant – The Bare Bones Basics

It is surprising how many women do not fully understand the mechanics of getting pregnant. For the majority of women, their menstrual cycles are 28 days long. Menstrual bleeding is only the beginning of the full cycle. Finding out how long your cycle is, is easy.  All you need to do is count the days between when two previous periods started.   Most women have cycles that are between 23 – 35 days long. Having unprotected sex around the time you are ovulating can result in you getting pregnant.  For women with a 28 day cycle, ovulation usually happens around day 14 or two weeks before your next period starts. The possibility of getting pregnant is present if you have sex during days 11 to 15 of your cycle.

Let’s take a look at what really happens in a woman’s body. At ovulation, an egg is released into the fallopian tubes. This happens at about 14 days after a woman’s period starts. The egg travels to the uterus (or womb), and can be fertilized anywhere along the route. The life of an unfertilized egg in the womb is a short one and in the absence of sperm will begin the process that leads to menstruation.

 

If You Have a 28 Day Cycle

The chances of getting pregnant during your period are very small if you have a 28 day cycle. If you aren’t sure how long your cycle actually is, you can calculate the length if you know when your period started during the last two months.  As long as you have normal 4 to 7 day menstrual bleed, you should not be fertile during that time.

 



Having Sex During Your Period Can Result In Pregnancy IF…

While uncommon, it is possible to get pregnant from having sex during your period. Cycle length and how long the menstrual bleeding lasts can play a part in an unexpected pregnancy. It all comes down to a numbers game. Women usually will ovulate about 14 days before their next period starts.

If your cycle is shorter in length than 28 days, there could be an increased chance of getting pregnant from having sex during your period.

For example, let’s say your cycle lasts 25 days instead of 28 days and your period bleeding lasts for 6 days. Healthy sperm can survive up to 5 days after ejaculation in the woman’s reproductive system. If ovulation occurs 14 days before your period is due, it would occur on day 11 of your cycle. If you had sex on day 6 of your period bleeding, the sperm could potentially survive until day 11, ovulation day. Having the sperm present and waiting at the time of ovulation could most definitely end up in a pregnancy.

Another time when you could get pregnant from period sex is when you have irregular cycles. When a female is in the early and late years of menstruation, her cycle often varies from month to month as well. Any one of these reasons, combined with unprotected sex, makes it possible for a woman to get pregnant during her period.

 

Sources:
Length and variation in the menstrual cycle–a cross-sectional study from a Danish county.
Münster K, Schmidt L, Helm P
Br J Obstet Gynaecol. 1992 May;99(5):422-9.