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    Can you get pregnant on your period? Your chances of conceiving during, after, and before menstruation

    Updated 24 March 2023 |
    Published 26 December 2018
    Fact Checked
    Medically reviewed by Dr. Jenna Flanagan, Academic generalist obstetrician and gynecologist, Beth Israel Deaconess Medical Center, Massachusetts, US
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    What’s the likelihood of conceiving on your period? How about just before or just after? We speak to a doctor for the lowdown on getting pregnant during menstruation.

    It’s that age-old question, and we’re here to answer it: Can you get pregnant on your period? We’ll get right to the point. Technically, the answer is a straightforward no: You can’t get pregnant while you’re on your period. 

    But hang on a second, because in practical terms, the answer is a little more complicated than that. If you’re having sex while on your period, and you’re not using any form of contraception, you shouldn’t assume that you definitely won’t get pregnant. 

    Why is that, exactly? It’s all to do with the timing of your fertile window. We’ll explain properly, but first, let’s do a quick refresher on exactly how you get pregnant and the fundamentals to know. 

    • Ovulation: During each menstrual cycle, one of your ovaries will release an egg in a process called ovulation. This little egg will travel to your uterine (fallopian) tube, where it will sit for around 12 to 24 hours.
    • Fertilization: If a sperm is in the uterine tube at the same time and fertilizes the egg, then pregnancy occurs.
    • Fertile window: You’re most likely to get pregnant during your fertile window, which is around six days long. This includes ovulation day and the five days before it (we’ll explain more on this time frame later on, as this is the part that’s most relevant).
    • Cycle length: As everyone’s cycle lengths are different, everyone will ovulate at different times and will therefore have different fertile windows. 

    Now that we know the basics, let’s take a closer look at the specifics. We know that people have a lot of questions about when exactly in their cycle they can get pregnant and particularly how their period could impact their chances of getting pregnant. So we’ll tackle the different stages of the cycle in chronological order and lay out the possibility of getting pregnant during each. Useful, right? We’ll also get a helping hand from Dr. Jenna Beckham, obstetrician and gynecologist, North Carolina, US, who will talk us through all the different factors to consider. 

    Can you get pregnant while on your period? 

    “In a very strict form of ‘Can you get pregnant when you are truly on your period, menstruating and shedding your endometrial lining?’ No,” says Dr. Beckham. “No, but with a big asterisk to proceed with caution.”

    That’s because when your fertile window falls (and, therefore, when you can theoretically get pregnant) totally depends on the length of your cycle. The shorter your cycle, the more likely it is that your fertile window will fall during your period, meaning there is a chance that you could get pregnant during that time.

    The average menstrual cycle is considered to be 28 days long. In a cycle of this length, ovulation tends to be around the midpoint, meaning that your fertile window would start five days before that and generally wouldn’t overlap with your period. However, a 2020 study using the Flo period tracker found that actually, only 16% of women had a 28-day cycle. Instead, experts agree that anywhere from 21 to 35 days is normal, but many people have cycles that are even longer or shorter than this.

    Why is this so important? Well, timing is of the essence when it comes to getting pregnant. After all, the sperm needs to reach the egg in the short window of time when the egg has been released and can be fertilized. As we’ve noted, there’s a possibility this could be when you’re on your period if your cycle falls that way. So essentially, period sex could lead to pregnancy in some cases.

    Just to complicate matters even further, it’s not only your cycle length that means getting pregnant on your period is technically possible for some people. Having irregular periods is a factor, too. These are pretty common. In fact, 29% of women experience changes in their menstrual cycle of up to 14 days. Some people also experience bleeding between periods, which can easily be mistaken for menstrual bleeding or a light period. As for the actual cause? Spotting between periods can be triggered by many things, with research suggesting that around 5% of menstruating women bleed during ovulation, for example. 

    If you occasionally bleed between periods, it can be more difficult to know with confidence when you’re actually menstruating and ovulating — and, therefore, when it could be possible for a sperm to fertilize your egg. “Unless you are doing specific, natural family planning and monitoring your cycle with exceptionally focused details, being on your period shouldn’t be used as a method of contraception,” adds Dr. Beckham.

    Of course, if you do want to track your periods to have an idea of when you’re ovulating, there are options available. Why not try Flo’s period tracker and ovulation calculator to give you an idea? And remember, if you’re comfortable with it, it’s perfectly OK to have period sex. It can sometimes just be a little messier. Just remember that having your period isn’t a contraceptive method, so have protected sex if you do not want to get pregnant. Your period also doesn’t protect you from sexually transmitted infections, so you may want to consider using a condom if necessary. 

    Can you get pregnant right after your period? 

    Simply put, yes. The phase from when you have your period until when you ovulate is called the follicular phase. Counting from the first day of your period, and depending on your average cycle length, the follicular phase can last anywhere from 10 to 16 days. The length of the follicular phase will have a really big impact on whether having sex right after your period can potentially lead the sperm to meet up with an egg that’s ready to be fertilized.

    Essentially, the shorter your menstrual cycle, the sooner after your period you’re able to get pregnant. For example, as Dr. Beckham explains, “If you menstruate every 21 days, then in those first few days after your period, you could be pretty close to ovulating again.” And if you’re close to ovulating, you could be in your fertile window. So, your chances of getting pregnant at any given stage of your cycle totally depend on what your cycle looks like. The more you get to know and understand your typical patterns, the more understanding you’ll have of your own fertile window.

    Can you get pregnant a week after your period?

    Yes, you absolutely can get pregnant a week after your period, says Dr. Beckham. If you track your cycle using an app like Flo, then you’ll have a better idea of exactly when you start to ovulate after your period. That can help you understand the possibilities of getting pregnant a week after your period.

    Plus, there’s something else to consider. Remember earlier on when we said the fertile window extends to the day of ovulation, plus the five days before? That’s because sperm can survive inside the uterus for up to five days. So if you’re having sex on your period, but you start to ovulate right after that (because you have a short cycle), the sperm may stick around and have a chance of fertilizing the egg when it’s eventually released. That’s why you shouldn’t assume that period sex won’t equal pregnancy, because in some short enough cycles, it’s possible.

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    How many days after your period can you get pregnant? 

    You have the highest chances of getting pregnant in the phase right before or during ovulation. That’s the fertile window, and as we’ve already mentioned, this lasts for around six days, to account for sperm’s ability to survive in your body for up to five days before ovulation. Ovulation itself happens about 16 days after the start of your period, but this differs depending on your cycle length. Ovulation anytime between day 11 and day 21 of your cycle is usually considered normal

    “You’re more likely to get pregnant if you have sex at least every other day between days 10 and 14 of a 28-day cycle,” Dr. Beckham says. But as we now know, not everyone has a 28-day cycle that runs like clockwork, so you should adjust this to suit you. In a shorter cycle, ovulation is likely to fall earlier, while in a longer cycle, it will fall slightly later. 

    In general, having sex every other day during your fertile window, depending on when that is (you can use an app like Flo to help you predict this), is a good bet for conceiving. One study found that couples who had sex every other day had a 22% chance of getting pregnant, and those who had sex every day had a 25% chance. However, other research suggests that sperm might need a little bit of a rest in order to be in top form for fertilization, so waiting two to three days between intercourse may help. The summary? There’s really no one-size-fits-all solution, and you should do what’s best for you and your body if you’re trying to conceive.

    Can you get pregnant right before your period? 

    So, we know that you can get pregnant during and after your period, but can you get pregnant a day before your period? How about three days, five days, or even seven days before your period? Yep, you guessed it: The answer all depends on the duration of your cycle. 

    Since, as we now know, a normal menstrual cycle can range from 21 to 35 days, you could potentially get pregnant at any of those times.

    Confused? We hear you. Let’s take a closer look at why that’s possible. The time from ovulation, when your egg is released, to the onset of the shedding of your uterine lining, when your period starts, is called the luteal phase. This will usually last between 10 and 16 days, but just like your menstrual cycle, the length of this phase can vary from person to person. 

    The day of ovulation can also vary. If ovulation is slightly later than expected, or the luteal phase is slightly shorter, it could mean the fertile window falls in the few days before you would normally expect your period. So in this scenario it could be possible to get pregnant if you have sex right before the time when your period would be expected.

    Make sense now? If you’re still a bit unclear, why not use our online ovulation calculator to spell it out according to your cycle?

    Can you only get pregnant during ovulation? 

    Or more to the point, can you get pregnant when you’re not ovulating? Essentially, the answer is yes. You’re most likely to get pregnant during the days of your fertile window, which as we now know, is in the direct run-up to ovulation plus the day of ovulation itself. 

    Can you take a pregnancy test while on your period? 

    Yes, there’s nothing to worry about here. You can take a pregnancy test while on your period, says Dr. Beckham. 

    “Being on your period or, in general, having bleeding does not interfere with the accuracy of the pregnancy test,” assures Dr. Beckham. Of course, if you’re on your period, then you won’t be pregnant. But if you’re experiencing bleeding that isn’t your period, then you could be. Wondering if it’s time to take a test? You can use Flo’s pregnancy test calculator to help you figure it out.

    Can you have a period and still be pregnant? 

    Remember, as we learned above, not all bleeding is menstruation. “So in technical terms, no, it’s not possible to have a menstrual period and to be pregnant,” says Dr. Beckham. On the other hand, “Yes, it’s possible to have all sorts of vaginal and uterine bleeding when you’re pregnant.

    “I have personally encountered patients who, for very long into the pregnancy or for a few months into the pregnancy, didn’t realize they were pregnant, and they thought they were having a period, when they were just experiencing bleeding,” she continues. 

    That often happens to people who don’t necessarily have very predictable, regular periods, those who don’t keep track of them regularly, or people who simply have a lot of variation in how long they bleed or how heavy their bleeding is, Dr. Beckham adds.

    Birth control to avoid getting pregnant on your period 

    If you’re taking birth control, and you’re doing so properly, that in itself will likely prevent you from getting pregnant. Of course, no birth control is 100% effective (apart from abstaining from sex completely, that is). To give you a more specific idea, using male condoms can lead to pregnancy 18% of the time, the pill 9% of the time, and the implant 0.05% of the time. As the effectiveness of birth control can vary greatly, be sure to chat with your doctor about the best option for you. And in case you were wondering, Dr. Beckham adds that there isn’t a dedicated birth control mechanism that is specifically targeted to preventing pregnancy during your period.

    Getting pregnant on your period: The takeaway 

    As we’ve seen, it is definitely possible to get pregnant while you’re on your period, but it totally depends on the length of your menstrual cycle. Remember that your fertile window will be around six days long because sperm can survive inside your uterus for up to five days. This means that for people who have very short cycles, having sex during your period could still allow sperm enough time to hang around and fertilize the egg after ovulation.

    So what does all of this mean if you don’t want to get pregnant? Essentially, if you’re having sex, you should consider using a method of contraception too. “Just being on your period alone should not be thought of as a pregnancy prevention method,” Dr. Beckham adds. 


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    History of updates

    Current version (24 March 2023)

    Medically reviewed by Dr. Jenna Flanagan, Academic generalist obstetrician and gynecologist, Beth Israel Deaconess Medical Center, Massachusetts, US

    Published (26 December 2018)

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