When I first started having sex, my primary care doctor — because I had yet to find a gynecologist — told me that the “safest” time to have sex was 10 days before your period and 10 days after you period. She explained that women ovulate about 14 days before their period.

It turns out, menstruation cycles are not exact from month to month. Trying to play it “safe” and not using a condom was just a disaster.  When I got pregnant on the Pill a few years later, my gynecologist explained “safe” times don’t exist, and nothing is a 100% guarantee. Which, of course, a positive pregnancy test had proven to be true; the human body is a fickle thing. As someone whose menstrual cycle is all over the place when I’m not on the Pill, I understood that, going forward, maybe I needed to add condom use to my Pill use.

Sex is much more enjoyable without unwanted surprises — the kind of surprises that pop up when you believe the myth that you can’t get pregnant on your period. Although uncommon, you can get knocked up when Aunt Flo is in town. But how?First of all, let’s look at a “normal” menstrual cycle and go over the basics:

What is a normal menstrual cycle?

“Normal”  is “about 21 to 35 days including a period during the first 3-7 days,” according to Dr. Didi Saint Louis, of Healthy Mommy, Happy Baby, Inc. “Ovulation occurs about 12-14 days before the first day of a period.”

So when am I most likely to get pregnant (i.e. most fertile)?

You may think you are most fertile just when you’re ovulating, but you would be wrong. As Dr. Hilda Hutcherson, clinical professor at Columbia University College of Physicians and Surgeons, explained a woman is most fertile one to three days prior to ovulation. And, don’t forget, sperm can live quite happily inside a woman for three to five days. Yes, that long.

How would it be possible to get pregnant on your period?Some menstrual cycles are fairly regular and normal, while others aren’t very normal at all. As Dr. Didi explained to me, there are two possible, irregular period scenarios that would lead to a big “oopsies.”

1. If a woman has a 21-day cycle, she may ovulate as early as day six of her cycle while still on her period and as late as day 10 of her cycle. If she has sex during her period, it is quite possible that she will get pregnant since she ovulates earlier in her cycle than someone with a 28 day cycle who may not ovulate until days 12-14 of her cycle.

2. If a woman has a 7-day period, she ovulates within 3 days of her period, so between days 10-12. And because sperm can stay alive in the body for up to 5 days, this woman could get pregnant if she had sex during day days 5-7 of her period.

Basically, it’s a late ovulation that occurs during a woman’s period or a situation in which a woman has sex during the last days of her period, but her ovulation isn’t that faraway, and those pesky sperm camp out for up to five days, just waiting to cause trouble. However, both Dr. Didi and Dr. Hutcherson stressed this scenario is very uncommon and unusual. In fact, stats on the number of women who have gotten pregnant while on their period were difficult to find.

The takeaway for us sex-loving ladies? You can’t go by your menstrual cycle to avoid getting pregnant and this is especially true for women with shorter cycles. But what you can you do is take every precaution to prevent a pregnancy by using contraception and using it correctly. You should be diligent in always taking your oral contraception at the same time everyday, and if you have an IUD or NuvaRing, you need to stay on the up and up with them. If your preferred method is condom use, then make sure you know exactly how to put on a condom the right way.

Taking preventative measures to ensure that you don’t end up with an unwanted pregnancy requires a bit of effort on your part. But since it’s an effort that contributes to keeping your baby days way in the future for when you’re finally ready for motherhood, then it’s an effort worth making. Don’t you think?

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