For some women, finding out they’re pregnant is an exhilarating moment: "We’re having a baby!" But for others, pregnancy is the last thing they need in their lives right now. Still, women who would like to avoid conceiving for an extended amount of time — or perhaps even altogether — might be wondering, "Can you get pregnant on your period?" Especially if their method of birth control recently failed. After all, the unexpected does happen, even to couples who are diligent about using contraceptives.
Whether you’re actively trying to conceive or ideally hoping to hold off on adding to your family, I'm willing to bet most women have likely wondered at some point: Can you get pregnant on your period? The short answer to “Can you get pregnant on your period?” is: It depends. But is is probable? Again, there are so many different factors to take into consideration.
It might be tempting to assume the answer to “Can you get pregnant on your period?” is a definite “no.” A woman’s uterus is in the process of shedding its lining, after all. So how could it be ready to support a pregnancy? This might seem like a straightforward answer on the surface. However, the actual explanation gets a bit tricky when you look at the details of ovulation, conception, and a woman’s unique fertility window.
First, let’s establish what is actually happening when a woman is on her period. Each month, the lining of a woman's uterus builds up in preparation to support a pregnancy. This happens with the help of her ovaries releasing more estrogen. About halfway through a woman’s menstrual cycle, an egg is released from one of her ovaries — a process called ovulation. "Prior to the release of the egg, the hormones in a woman's body increase to prepare (and thicken) the lining of the uterus in case the egg is fertilized and a pregnancy occurs,” Dr. Michele Hakakha told Parents magazine. “If there is no fertilization, the lining of the uterus is sloughed off about 14 days later. This is called your period."
Now let’s take a look at some factors that determine the answer to “Can you get pregnant on your period.” Such as...
How long is your menstrual cycle?
According to WomensHealth.gov, the length of a menstrual cycle is counted starting on the first day of your period up to the day before your next period. A typical cycle is about 28 days long. However, everyone is different — and the length of a woman’s menstrual cycle can actually vary from month to month. As long as your periods usually come every 24 to 38 days, they’re still considered to be “regular.”
Plenty of women, however, have irregular menstrual cycles. This can make it difficult for them to determine their fertility window — another factor when it comes to the question: "Can you get pregnant during your period?"
When is your fertile window?
If your menstrual cycle is regular, then you might be able to estimate when ovulation occurs by simply counting back 14 days from when you expect your next period. This is referred to as the calendar method, according to BabyCenter. Your fertile window includes the day of ovulation, along with the five days leading up to it. (This simple ovulation calculator tool can help you quickly figure out your fertile window.)
It’s worth noting that the calendar method isn’t the most accurate way to determine your fertile window if you’re trying to conceive. Charting your basal body temperature or using an ovulation kit are better ways of doing so ahead of time. However, since we’re trying to find the answer to the question, “Can you get pregnant on your period?” the calendar method is what you’d be using. Which brings us to the next factor in the equation ...
How long can sperm survive inside a woman’s body?
This bit of information is key to the question, “Can you get pregnant on your period?” Because as it turns out, sperm can live inside the female reproductive tract for up to five days, according to Medical News Today. Meaning unprotected sex toward the end of a woman’s period increases the likelihood of pregnancy.
Which brings us to the primary question at hand ...
Can I get pregnant during my period?
It's highly unlikely. A woman with a 28 to 30 day cycle and an average period lasting two to eight days probably won’t get pregnant during her period. However, special circumstances make it possible for certain women to become pregnant during their period. "Usually, you ovulate about two weeks after your period starts, long after sperm are dead," Dr. Lynn Borgatta, a professor in the department of obstetrics and gynecology at the Boston University School of Medicine, told Cosmopolitan. "But in a short cycle, you may ovulate only a few days after your period ends, while sperm are still alive — making fertilization possible."
Additionally, some women have bleeding between their periods called breakthrough bleeding — which can happen during ovulation but be mistaken for a period. (How convenient, right?) This can make it hard for a woman to determine where, exactly, she is in her menstrual cycle.
Can I get pregnant during my period if I’m on the pill?
In the same light, plenty of women have likely wondered if it's possible to become pregnant while having a period and taking birth control pills because this is during the week that she takes the inactive pills. The thing is, oral contraceptives aren't 100-percent effective even when women use them perfectly. And when used typically, in fact, the pill is considered 91 percent effective, according to Everyday Health.
Theoretically, a woman could indeed become pregnant during a period while taking the pill. Especially if she doesn't take the pill at the same time every day, or if she happened to miss a dose. Still, if you're taking the pill correctly and consistently, the week of inactive pills protects against pregnancy as well as as it does during any other time of the month.
In conclusion, yes, you can get pregnant on your period. The odds are extremely small, considering you'd have to have a short menstrual cycle to begin with, then have unprotected sex toward the end of your period, and ovulate very soon after your period. But it's definitely possible.
So unless you're comfortable with the idea of a potential pregnancy, it's best to be using some sort of contraceptive at all times — even during period sex.