Ovulation – what is it and how can you tell when you’re ovulating?

6th January, 2022 • 7 min read

What does ovulation mean?

Ovulation happens as part of your monthly menstrual cycle. It's when 1 of your ovaries releases an egg and if this egg is fertilised by sperm, you can become pregnant.

Once your periods start during puberty, you’ll usually release an egg (ovulate) about once a month until you reach the menopause – when your periods stop and you’re no longer able to get pregnant.

Understanding more about ovulation, and the signs to look out for, can be helpful if you’re trying for a baby. Read on to learn more.

What can it tell me?

You’re most fertile around the time that you ovulate, so knowing when it happens can help you work out the days in a month when you’re most likely to get pregnant. If you’re trying for a baby, it means you can plan to have sex around this time.

On the other hand, it’s also important to know when you’re ovulating if you’re using

natural family planning
(fertility awareness) to try to avoid getting pregnant, rather than hormonal or barrier methods of

What are the signs of ovulation?

An average menstrual cycle is often said to last 28 days, but this can range from 21- 40 days, with day 1 being the first day of your period. Ovulation usually happens around the middle of your cycle, and if you’ve got a 28 day cycle, it will occur 10 to 16 days before the start of your next period.

Having said this, everyone’s cycle is different and yours may be longer or shorter, which can mean you have a different ovulation, or fertility ‘window’.

If you have a regular cycle, you can use an online ovulation calculator to work out your window based on the date of your last period and your usual cycle length.

There are also other signs that can help you pinpoint your ovulation window, including:

  • changes in body temperature – your resting, or ‘basal’, body temperature rises slightly during ovulation. You can use a basal body thermometer to record your temperature each morning, before you do any activity, for several months, to help you identify a pattern. The 2 or 3 days before your temperature rises are usually when you’re at your most fertile
  • changes in cervical mucus (the fluid produced from the neck of your womb, or cervix) – everyone’s different, but you may notice a change in your
    vaginal discharge
    around ovulation. It’s often clearer, wetter and more slippery than usual, and is sometimes described as being like stretchy egg white
  • changes in hormone levels – an ovulation kit can measure your hormone levels. It’s similar to a home pregnancy test: you usually pee on a test strip and wait for the result. But bear in mind that these kits are designed to show when you’re meant to ovulate – they don’t actually influence ovulation

Some people also get ovulation symptoms, such as

sore breasts
, mild
tummy pain
or an
increased sex drive
. But these can be caused by lots of things, and aren’t reliable ways of working out when you’re ovulating.

What happens during ovulation?

Your reproductive system has 2 small sacs called ovaries, which contain all your eggs. Once a month, around the middle of your

menstrual cycle
, an egg is released from 1 of your ovaries. It then travels down into 1 of your 2 fallopian tubes, where it can be fertilised if it comes into contact with sperm.

At the same time, the lining of your womb (uterus) gets thicker. If your released egg is fertilised in the fallopian tubes, it continues down to your womb and fixes (implants) into the thickened lining – and


However, if the egg isn’t fertilised, your womb sheds its thickened lining, and this and the unfertilised egg leave your body through your vagina as your


This is why missing a period is one of the most important

signs of pregnancy

Read more about

how many eggs a woman has throughout her lifetime

Can you have periods if you’re not ovulating?

Not releasing an egg during your menstrual cycle is known as anovulation. Technically, you need to ovulate to have a period: your period is what happens when your body recognises that an egg hasn’t been fertilised.

However, it’s possible to still have a bleed if no egg is released. This is called anovulatory bleeding. When your bleeding is irregular, it's called

abnormal or dysfunctional uterine bleeding (AUB
). It’s caused by an imbalance in 1 or more hormones.

You should see a doctor if you notice any unusual bleeding or if you’re concerned about anovulation.

I need help getting pregnant – when is my best chance?

After an egg is released, it only survives for 12 to 24 hours if it isn’t fertilised. However, sperm can live inside you for up to 5 days after you have sex.

This means you could have sex up to 5 days before you ovulate and still get pregnant, if the sperm and egg meet within 24 hours of the egg’s release.
However, it’s thought that the best chance of pregnancy is when the sperm and egg meet within 4 to 6 hours of ovulation.

To increase your chances of getting pregnant, you can:

Read more about

how to increase your chances of getting pregnant

When to see a doctor

You should see your doctor if you’ve been trying to get pregnant for more than a year. See them sooner if you're 35 or over or have another health condition that may be affecting your fertility. They can offer advice and check for any issues with ovulation or other areas of your fertility. Problems with ovulation are one of the most common causes of


You should also see a doctor if you have:

  • irregular periods
    , unusual bleeding or if your periods are very light or stop and there’s no obvious reason (such as the
  • severe
    period pain
    , very
    heavy periods
    , lower tummy or back pain that gets worse during your periods, or pain during sex or when you pee or poo
  • obesity
    – these may have an impact on your ability to get pregnant
  • problems with excess facial or body hair, or acne
  • any underlying medical problems that could be affecting ovulation, such as
    thyroid problems
    or medication for other conditions

Your health questions answered

  • How long does ovulation last?

    Ovulation only lasts for one day - when the hormone changes in your body (usually in the middle of your menstrual cycle) trigger the release of an egg from your ovaries. The egg then travels towards your uterus (womb) but is only able to be fertilised for 24 hours. However, sperm are able to live in the uterus and fallopian tubes for up to 5 days which means there are typically 5-6 days in each cycle that you can become pregnant if you are not using contraception. The days during each cycle when you are most fertile, and therefore most likely to get pregnant from unprotected sex, is a day or two either side of ovulation.

    Dr Roger HendersonClinical writer
    Answered: Invalid Date
  • Can I get pregnant while I’m on my period?

    While you can’t actually become pregnant while you’re on your period, you can get pregnant after having sex during your period. This is because sperm can survive in your body for up to 5 days after you have sex. So if you have a short menstrual cycle – for example, 21 days rather than 28 – you could ovulate soon after your period ends, and the surviving sperm could fertilise your egg.

    Healthily's medical team
    Answered: 01/06/2022
  • Can you ovulate twice in a month?

    Usually you’ll only have one ovulation in a month, releasing one egg from your ovaries. Some people will ‘hyperovulate’- this means they release more than one egg each cycle which can result in twins, or other numbers of multiples. Two small studies have shown the possibility that some women may have two or three ‘waves’ of hormones that could cause egg release each month. More research needs to be done to get a clearer picture.

    Dr Roger HendersonClinical writer
    Answered: Invalid Date

Key takeaways

  • ovulation is part of your monthly menstrual cycle, when an egg is released from 1 of your ovaries
  • knowing when you’re ovulating can help you increase your chances of getting pregnant, as this is your most fertile time
  • if you have a regular 28-day cycle, you’ll ovulate around 10 to 16 days before your period starts – but everyone has a different ovulation ‘window’
  • other signs of ovulation include a rise in body temperature and a change in vaginal discharge
  • see a doctor if you have any concerns about your periods or fertility

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.