Sex before your period – can you get pregnant?

If you don't want to get pregnant and you're thinking of protecting yourself by only having sex shortly before your period, think again! Although the chances of pregnancy are lower because ovulation has most likely already taken place, that's no guarantee that you won't conceive.

Every instance of unprotected intercourse carries a risk of pregnancy – whether smaller or greater. So yes, you should protect yourself every single time, because there are situations in which you can get pregnant even before your period. In the sections below, we explain exactly which factors influence this likelihood.

What is ovulation and when does it happen?

One crucial factor that influences the possibility of pregnancy – and the reason why it's so low just before menstruation – is ovulation. With a regular cycle of 28–29 days, ovulation usually occurs on day 14.

During ovulation, the ovaries release a mature egg which may or may not be fertilised. If it meets a sperm cell, the fertilised egg then implants in the lining of the womb and pregnancy begins.

Ovulation is so important for a pregnancy to occur because the egg survives for a maximum of 24 hours. If it isn't fertilised within this time, it breaks down and is shed during your period along with the tissue of the womb lining and menstrual blood.

That explains why the chances of getting pregnant 1–2 days before your period are considerably lower – because ovulation has most likely already happened. After ovulation, the likelihood of pregnancy drops dramatically, as there's no longer an egg available for fertilisation.

Even so, we told you at the start of this article that unprotected sex before your period doesn't guarantee protection against pregnancy. Why? Because you can never know exactly when you ovulate. Every body is different and hormone levels fluctuate from month to month, so ovulation can occur earlier or later even with regular cycles – and especially so if your cycle is irregular.

What happens if your cycle and ovulation are irregular? 

With an irregular cycle, it's far harder to correctly judge your fertile days and the start of your next period. If the length of your cycle varies from month to month, you can't rely on ovulation taking place on day 14. You can't plan intercourse for ‘just before your period’, because for one thing you don't know when your period is due, and for another you can't be sure that ovulation has already happened – which means pregnancy is possible.

Causes of cycle disorders

Some women have an irregular cycle right from the start. In some cases it settles down in the first few years after the first period. In others, menstruation remains irregular, which makes pinpointing the fertile days very difficult.

There are many possible causes of such cycle disorders, which we've discussed in more detail HERE. The most common include:

• Polycystic ovary syndrome: irregular bleeding is a common symptom of PCOS, which we've told you all about in another article on the Enroush blog.

• Uterine polyps: a common cause of spotting, irregular and heavy periods, as well as bleeding after intercourse, is uterine polyps.

• Stress: with a stressful lifestyle, the brain releases larger amounts of cortisol, which can delay your cycle. You'll find more information about stress and how it affects your period HERE.

• Endometriosis: this is a common cause of cycle disorders, particularly very heavy bleeding and severe pain. If you'd like to read more about endometriosis, how to recognise it and what we know about it so far, you'll find an article HERE.

• Eating disorders: a diet lacking in essential nutrients, or marked by excesses of any kind, can cause hormonal imbalances and weight problems, which in turn lead to cycle disorders.

• Age: it's normal for the cycle to be irregular in response to hormonal changes – especially in the first few years after your first period and in the final years, as the menopause approaches.

When can you get pregnant before your period?

If you have a completely regular cycle and know exactly when your period is due each time, it's easier to track and correctly judge your fertile window. That way you can work out (roughly) how many days before your period you can't get pregnant.

However, the likelihood of pregnancy before your period increases in the following cases:

• If ovulation occurs later than usual, for example as a result of raised cortisol levels following a stressful period or because of changes to your diet. If fertilisation happens at precisely that moment, a pregnancy can occur.

• If you have an irregular cycle, because you can't tell when you're ovulating.

• If you mistake ovulation bleeding for menstrual bleeding, without realising that you're actually in your fertile window.

How do you avoid getting pregnant before your period? 

Whether before your period or at any other point in your cycle: if you don't want to get pregnant, avoid unprotected intercourse. These are the methods available to protect yourself:

• Use contraception: you have plenty of options, including the condom (the only method that also protects you from sexually transmitted infections), the pill, the coil or other effective contraceptives.

• Use emergency contraception: if you've had unprotected intercourse, emergency contraception can prevent a pregnancy, provided it's taken as soon as possible within 72 hours.

How can you tell whether you've become pregnant after unprotected sex before your period? 

A missed period is the clearest sign of a possible pregnancy. If you know you had unprotected intercourse before your period was due, it makes sense to keep an eye on whether your period is late or doesn't arrive at all. There are also other symptoms that count among the earliest signs of pregnancy:

• Implantation bleeding, which can appear as light bleeding 10–14 days after fertilisation and may be mistaken for a period.

• Nausea, vomiting and fatigue, as progesterone levels in the body rise.

• Increased tenderness or pain in the breasts, which may also increase in size.

When should you take a pregnancy test?

If your period doesn't arrive, you notice other early symptoms, or you suspect you may be pregnant after unprotected intercourse, pregnancy tests are the simplest, quickest and most reliable way to confirm whether or not you're pregnant. If the result is positive, it's a good idea to see your doctor to decide how you'd like to proceed and discuss the next steps.