Can you get pregnant if you have sex on your period?

In short - yes, you can.

The chances of this happening aren’t as high as they are at other times of the month, but it’s definitely possible.  

To understand how, let’s break down what happens in the body during the times between a period, known as the menstrual cycle. There are four stages of the overall menstrual cycle and they all do something a little bit different.  

The stage that we are all likely to be familiar with is the one where we have our period. This is when our body gets rid of the lining of the uterus – why? Because there’s no pregnancy. This is called menstruation.   

While we’re having our period, our body is already thinking about next month, and getting ready for another chance to get pregnant. So a message goes out for another egg to start to mature in the ovaries (where all the eggs hang out). The technical term for this is the follicular phase, and it usually takes around 13-14 days. Essentially, it’s the body getting the egg ready to be released from the ovaries. 

The next stage is when the egg is finally ready to be sent out from the ovaries, and it takes a little journey through the fallopian tubes towards the uterus, kind of like a subway going through a tunnel to get to the next station. This is a really short ride for the egg but it takes kind of a long time – usually between 16-32 hours to move from the ovary to the uterus, and this process is called ovulation.  

The last part of the cycle is known as the luteal phase, where the lining of the uterus is thickening, getting ready to be a nice cosy space for a fertilised egg to hang out - just in case you get pregnant. And here, you get to the crossroads. If the egg is fertilised by sperm on the way to the uterus, it will implant itself in this lining to grow. But, if pregnancy doesn’t happen, then the egg is reabsorbed into the body and the lining of the uterus is shed again in menstruation, and then the cycle starts all over again.  

Women are most likely to get pregnant in the five days before the egg sets out from the ovaries, and on the day that it does head out. Interestingly, the egg only lives for 24 hours after it leaves the ovaries, so it has to meet a sperm cell before this time is up in order for pregnancy to happen. 

So how come you can still get pregnant if you have sex while you’re on your period?  Well, sperm are actually very patient, and they can live for up to five days in the female body. So that means that if you have sex while you’re on your period, and there’s not a lot of days between your period and your ovulation, the sperm might actually get a chance to meet an egg. Hey baby... 

Another thing to think about is that we all have our own menstrual cycles and they aren’t always exactly the same number of days. You and a friend might have cycles that last a different amount of time, and your own cycle can also change in length. Usually though, it’s around 28-30 days. People who have a shorter cycle have a bigger chance of getting pregnant if they have sex on their period, because there’s less time between having their period, and their egg leaving the ovaries.  

So the bottom line?  

Your chances of pregnancy change depending on where you’re at in your menstrual cycle, but they are never totally zero. If you’re wanting to avoid pregnancy, make sure you’re using contraception. 

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