Updated August 24, 2015.

Question: Can I get pregnant if I had sex while I was on my period?

Answer: The quick answer is, yes, you can potentially get pregnant if you have sex during your period (menstrual cycle). Sperm can survive for days inside your reproductive tract. So say you have sex towards the end of your period, but ovulate only a few days later, ovulation is close enough to unprotected sex, that you are pregnant.

The other problem is that many women may have irregular cycles, making it harder to predict what day of your cycle you are on.

"I heard it from a girlfriend, and I have no idea where she learned it from," said J, who didn't want her name used. "It made sense when I thought about it on a surface level. I just didn't think through the man's side of it. Oh goodness, I'm so lucky I didn't get pregnant."

The truth is that it is unlikely during the first day or two of your cycle, but this is not a method of birth control. Therefore you can't rely on sex during your period to prevent pregnancy. That is certainly a bad combination. So what do you do if you had sex on your period and now you think you might be pregnant?

A pregnancy test is the best way to tell if you are pregnant or not. You must wait until you miss your next period to get the most accurate results. This can be a home pregnancy test or a pregnancy test from your doctor, midwife or health department.

If you are trying to avoid getting pregnant find a real method of birth control.

Condoms, birth control pills (oral contraceptives), intrauterine device (IUD), foams, Depo provera shots, patches...there are plenty of methods to choose from. Be sure to ask your midwife, doctor or local health department for advice on the method that is best for you. They should ask you a series of questions to help you figure out what works. 

Part of what they will ask will include:

• How often you have sex
• When you may want to look at being pregnant (if at all)
• If you are in a monogamous relationship
• medical history

This will help you pick the method that is most likely to prevent pregnancy and work in your life.

Many women say that they thought pregnancy was unlikely to happen because the uterus was shedding it's lining. What most people don't understand is that a fertilized egg does not embed into the uterine lining for many days after conception. The sperm and egg tend to meet in the outer third of the Fallopian tube. Then it takes a few more days to travel the tub to embed into the uterus. And before then, a pregnancy test won't even think about turning positive, because the hormone hCG is not being produced. 

Source:

Weschler, T. Taking Charge of Your Fertility. Harper Collins. 2006.