Can You Get Pregnant When You're On Your Period? Here's What A Doctor Has To Say

There needs to be more open talk around women’s health care, especially the topics that confuse us. That’s why we want to address the age-old question: can you get pregnant while you’re on your period?

This is a conundrum that has sent pregnant rumors around many a high school health class for years. We’ve always wondered, especially because we’ve always heard various answers on the topic. So to finally put this query to rest, we spoke with Alyssa Dweck, M.D., a gynecologist with a practice in New York and author of the upcoming book The Complete A-Z For Your V. Because we know you were wondering just as much as we were. 

The short answer is yes, you can absolutely get pregnant on your period. 

The longer answer is there are so many factors to this question. While the chances of your getting pregnant on your period are lower than other points in your cycle, it really depends on your own personal cycle.

Not all vaginal bleeding is necessarily your period, so unless you have a perfect 28 day cycle and have been tracking it, you could be risking pregnancy. Dr. Dweck puts it this way:

“Not all vaginal bleeding is your period. If you’re on your period and your uterine lining is shedding the answer is you’re not going to get pregnant.”

“However, there are so many nuances to this because some women have irregular periods,” Dr. Dweck continues. “They may not realize they have the potential for getting pregnant.”

Why might you have vaginal bleeding without having your period?

Dr. Dweck lists anything from your birth control method, hormonal imbalance, thyroid irregularity, structural issue, abnormality of the cervix, or a vaginal infection.

For example, she says many women spot throughout their use of hormonal IUDs. She also says that some women spot when they’re ovulating. The upshot is that if you’re bleeding it might not be your period. It isn’t a reason to freak out, but it does mean that if you’re not keeping good track of your cycle and are having unprotected sex, you could be risking pregnancy.

So what’s a girl to do? Dr. Dweck highly recommends getting to know your own body and your own cycle. Once you know what’s normal for you and your body, you can make better decisions about your health and birth control methods.

“It’s really helpful to get to know your own cycle,” Dr. Dweck tells HG. “If you have your period every 28 days you can predict exactly when you’re ovulating.” In that case, sex during your period shouldn’t pose that much of a risk for getting pregnant.

“But if you’re someone with really erratic bleeding, you can’t really know if you’re bleeding is due to an egg not being fertilized or something else,” Dr. Dweck instructs. “It might be unsafe to have sex during that time.”

Being conscious of your ovulation is key, since Dr. Dweck says that’s the time you’re most likely to get pregnant. She goes on to say that when you’re ovulating your ovary is sending out an egg. After that happens you have a 72 hour (3 day) window of when you could get pregnant.

On top of that, sperm can live up to five days inside the female body. So if you have sex while you’re on your period and you don’t have a regular cycle, you might ovulate a couple days after you finish menstruating—and if the sperm is still alive inside of you, you might end up pregnant.

As always, Dweck says that the best way to avoid pregnancy is birth control. 

Dweck reminds us that even though you can avoid pregnancy while having sex on your period, it is always better to be safe than sorry.

“If you’re on birth control, the period typically occurs at a very predictable time,” Dr. Dweck tells HG.

Being on birth control such as the pill gives you protection that’s 98-99 percent effective. “Unless you missed a pill or are very unlucky you will not get pregnant when you’re on the pill,” Dr. Dweck says.

But how did having sex on your period to avoid pregnancy even become a thing? Dr. Dweck points out a really important piece of insight: Women won the right to birth control pills in the US in 1965. Before that, women had to rely on knowing their own cycle to family plan. That’s how it became known that having sex on your period was a method for avoiding pregnancy. That’s the method they were using for a long time.

The upshot is you’re not likely to get pregnant while having sex on your period.

However, being sure you’re on your period and not ovulating is harder than you might think. So if you’re not planning on making a new addition to your life any time soon, it’s better to learn as much as you can about your body, because you don’t want to play with the odds.

So be safe out there, and always use protection!