There are many reasons you may be asking, “Can you get pregnant on your period?” Maybe you’ve already had a kid (or two or three) and are trying to have birth control-free sex without getting pregnant. Or maybe you’ve been trying to get pregnant for a long time, and having sex between periods hasn’t been working.
It’s worth asking if you can get pregnant while on your period instead, right? (You might also be interested in the best fertility supplements and teas for fertility, too!)
The answer to whether or not you can get pregnant on your period is actually yes, “but…” – and I’ll explain exactly why. But first, let’s go over the mechanics of your menstrual cycle and how it relates to getting pregnant.
How Your Menstrual Cycle Works
The first day of your cycle is always the first day of your period. This means if you don’t know when the first day of your last period was, you can’t determine what day of your cycle you’re on!
Periods are usually 4-5 days for most women, but they can be literally any length, because bodies are weird and go through all kinds of altering circumstances. A period can be as short as two days, or seem to stretch on to infinity (usually requiring medical intervention).
Personal example: My very first period never. ended. After about three weeks of bleeding, it was only getting heavier. I was severely anemic, paler than normal, and on the verge of fainting when my mother noticed something was wrong! I had to be put on birth control pills to get it to stop and stayed on them for over a year. When I stopped the pills, my periods were normal on their own.
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Ovulation
Ovulation is when an ovary releases an egg, which can be fertilized to conceive a baby. This usually happens mid-cycle. The timing doesn’t really have anything to do with how long your period is. The time between full cycles is the best way to estimate this window though, so you’d probably need to track your periods for several months to get a good idea. You can also try to analyze your cervical mucus for ovulation discharge. Once an egg is released, it “lives” for about 12-24 hours, waiting to meet sperm.
The average woman’s cycle is 28 days, which means the 14th day (13 days from the start of your period) is usually when ovulation occurs. The middle of your cycle may not be your personal window of fertility, though. Once again, I’m a bit of a weirdo in this department – and I never knew it till my husband and I started trying for our first baby.
After several months of trying without any luck, I bought some ovulation predictor tests. I used one every morning starting from the 14th day of my 30-day cycle… and it took six days before I got a strong positive! And guess what? I got pregnant that night! My second baby was also conceived very late in my cycle.
So for me, having just a slightly longer-than-normal cycle of 30 days, I still ovulated much later than normal at day 20-21. This is why the “rhythm method” of contraception should never be relied on unless you are 100% sure of your ovulation pattern!
So, can you get pregnant on your period?
The surprising answer to this question is both yes AND no! I’m going to explain the yes in detail, but first let’s answer why it’s technically “no”:
Can you ovulate on your period?
No, you physically cannot ovulate during your period (at least, not while your uterus is still actively shedding its lining). Some women have a light flow of “residual” bleeding after their uterus has finished contracting to shed its lining, and there’s an infinitesimal chance of ovulating during this time.
But then…
How can a woman get pregnant on her period?
YES, you CAN get pregnant “on your period” because you can have sex during your period and get pregnant later as a result! This is because sperm can live in your body for up to 5 days (and yes, sperm can survive in menstrual blood). So you could ovulate right after the end of your period, and that egg could meet sperm that’s already been waiting for several days to fertilize it.
Crazy, right?? So let’s talk about this a little bit more.
What are the chances of getting pregnant on your period?
The chances of getting pregnant while on your period are still extremely slim. We’re talking less than a 1% chance during the days that you’re bleeding. But it’s not zero – meaning there are women who have gotten pregnant during that time before (and there will be again!). Keep in mind that when we say “got pregnant during her period,” it just means she had sex while on her period that led to her fertilizing an egg shortly after her period ended.
The chances go up a little bit every day after the first couple of days of your period, and are about 42% the day before ovulation (which is actually more “fertile” than the day OF ovulation).
What if you have irregular periods?
For some women, irregular periods mean ovulating at irregular times – from the day after your period all the way to the days right before a new period starts. If you ovulate the day after your period, having sex during your period actually gives you a pretty high chance of getting pregnant when you ovulate!
However, many women with irregular “periods” aren’t actually having periods. It’s actually an anovulatory cycle paired with excessive bleeding caused by a drop in progesterone or estrogen, or simply an unsustainable buildup of uterine lining that must come out. This is very common in women who suffer from PCOS.
The only way to know for sure whether or not you’re ovulating is to use ovulation predictor tests throughout your entire cycle.
Can you get pregnant at the end of your period?
If you have a very short menstrual cycle, there’s actually a pretty decent chance you could get pregnant after having sex at the end of your period.
Even if you have a regular 4-week cycle, if your period lasts an exceptionally long time – say, 10 days or so – you’re increasing your odds of getting pregnant if you have sex near the end of that period (because it’ll be so close to your predicted ovulation window).
Can you get pregnant right after your period?
Yes, even moreso than having sex at the end of your period. In fact, this is the point in a woman’s cycle where she’s most likely to get pregnant when she thinks so won’t – because many women with short cycles ovulate within five days of the end of their period.
Remember, the sperm could be hanging out for up to five days after sex!
Can you get pregnant the day before your period?
Yes, but it’s extremely unlikely during this time – simply because a genuine period is triggered by the breakdown of the corpus luteum, which happens due to an egg not being fertilized. You’d have to ovulate, then have a rapid drop in hormone levels or some other anomaly to trigger bleeding the very next day.
You could still have a fertilized egg traveling down your fallopian tube, though, which shows up after a new uterine lining has formed to implant! This is extremely rare, though.
More than likely, if you ovulate the day before your “period,” you’re not really having a true period, and your uterine lining is shedding due to hormonal imbalances.
Can you get pregnant on your period while on birth control?
The “period” that happens during the placebo or “sugar pill” week of your birth control pack is not a true period. Just like women NOT on birth control who have an anovulatory cycle, you’re really just bleeding due to a drop in the hormones provided by the active birth control pills. This is often called a “withdrawal” bleed.
Birth control, by design, should prevent you from ovulating – so whether you’re having sex on or off your period, you’re not likely to get pregnant until you stop taking it.
What if you’re bleeding when you would normally ovulate?
This is actually a super common occurrence, and bleeding during ovulation doesn’t mean you’re having a period OR that you’re not pregnant. Many women have breakthrough bleeding for a day or two during and after ovulation, and it’s usually caused by high levels of progesterone or LH.
So if you already know you should be ovulating about now, but you think you’re getting your period, don’t think it’s because you’re not pregnant! If the blood is a lighter red or pink, it’s likely just spotting and not your real period. You can get your “period” and still be pregnant in the first month – just know that if you’re pregnant, it’s not really a period, but some other reason for bleeding.
When can a woman not get pregnant?
What they told you in high school is actually true: there is no safe time to have sex and have a 100% chance of NOT getting pregnant. Abstinence from penetrative sex and getting semen in or around your vulva is the only way to prevent pregnancy for sure.
That being said, if you have sex on your period WITH a condom, your odds of getting pregnant diminish to next to nothing. If you’re comfortable with a one in a million chance of getting pregnant, go for it!
How rare is it to be pregnant and have your period?
Well… it’s so rare, it’s impossible.
Since we discussed the fact that a period is only triggered by an egg not getting fertilized, if you’re bleeding and pregnant, it ain’t a period. It’s likely breakthrough bleeding, implantation bleeding (meaning you are definitely pregnant!), or bleeding from a sudden drop in hormones.
Either way, if you’re bleeding and you’ve had a positive pregnancy test, you should get to your doctor ASAP!
The Best Time to Have Sex to Get Pregnant
The absolute best time to have sex to get pregnant is not, for the vast majority of women, while on your period. It’s the day or two before ovulation, to ensure sperm is hanging around during that 12-24 hour window when the egg is released and ready to be fertilized. Check out success stories from having sex two days before ovulation!
For some women, this means the best day to have sex to get pregnant would be the day after their period; for others, it’ll be right at the mid-cycle point; and for others, like me, it can be even later in their menstrual cycles, even just a few days before their next period is due.
Why Your Ovulation Window Might Have Changed
Even if you’ve tracked your periods or taken ovulation predictor tests in the past to determine your fertile window, your ovulation pattern could have changed since then. Factors that can affect when you ovulate include:
- hormonal changes
- weight fluctuation
- stress
- thyroid problems
- PCOS
- breastfeeding
- prescription, OTC, and natural medications
I always think of “stress” as a catch-all, because who isn’t stressed in this day and age? So if you think your ovulation pattern may have changed – or stopped completely – you can talk to your doctor or use ovulation predictor tests to help pinpoint it again.
If you’re trying to avoid getting pregnant right now, no time for sex is 100% foolproof, so use birth control and/or condoms to be safe. If you ARE trying to get pregnant and it hasn’t been working out so far, having sex on your period isn’t likely to help you any unless you have extremely short cycles with nearly back-to-back periods. Your first step should be to pinpoint your ovulation with hormone-reading tests, and have sex as soon as they tell you to!
