How conception works

For the best chance of getting pregnant, you need to get your fertile eggs and your partner's sperm together as often as possible.

How the menstrual cycle works

  1. Your cycle starts on the first day of your period and continues up to the first day of your next period.
  2. At the same time, eggs begin to mature in the ovary.
  3. The lining of the womb starts to thicken in readiness for fertilisation.
  4. During ovulation your cervical mucus becomes thinner and clearer to help the sperm to reach the released egg.
  5. About 10 to 16 days before the start of your next period, an egg is released from one of the ovaries (ovulation).
  6. If sperm is present at the moment of ovulation, or some time during the next 24 hours, the egg may be fertilised.
  7. If the egg has not been fertilised, the egg is re-absorbed by the body, the hormone levels drop, and the womb lining is shed – the beginning of your next period.

Now that you know all about your menstrual cycle, read our top tips for getting ready to conceive.

Have more sex!

The best thing to do to boost your chance of conceiving is to have regular sex throughout your cycle.

Time sex right

To boost your chances of conceiving, aim to have regular sex throughout your cycle so you know that there should hopefully be good-quality sperm waiting when the egg is released. An active sex life is all most people need to conceive.

If you are quite sure when you ovulate each month you can give yourself the best chance of getting pregnant by having sex in the days leading up to ovulation. Continue having sex during ovulation. After this your fertile time will be over for that cycle.

When does ovulation happen?

Ovulation usually happens about 10 to 16 days before the start of your next period, so  it helps to know your cycle length before you start trying to conceive.

You may never have considered when you might ovulate within your cycle, and if you have been using a hormone contraceptive such as the Pill, you won’t have had a natural menstrual cycle for a while.

As a first step, mark on your diary the dates that you bleed during a period. You can then count how many days from the first day of your period to your next period to work out the length of your cycle.

There are also apps available that can help you monitor your cycle.

Cervical mucus changes

The cervix secretes mucus throughout the menstrual cycle, starting off sticky white and gradually becoming thinner and clearer.

Before and during ovulation the mucus increases and becomes much thinner, slippery and stretchy. Women often compare it to raw egg white.

This thinner mucus is designed to help the sperm swim easily through it. It indicates that you are in your fertile phase, so this is the time to have sex if you want to get pregnant, but use contraception if you do not!

The last day you notice the wetter secretions is sometimes known as ‘peak day’ and for most women this occurs very close to the time of ovulation.


You can also find out about your menstrual cycle by keeping a note of your temperature each morning when you wake up. Your temperature rises by about 0.2°C when ovulation has taken place.

As it is only an indicator that you have ovulated, and doesn’t tell you when your fertile time starts, this is not very useful for most women.

Using ovulation predictor kits (OPK)

Ovulation predictor kits are available from chemists and are fairly simple to use. They work by detecting a hormone in your urine that increases when ovulation is about to take place.

The simplest urine kit tests for luteinising hormone (LH), which surges 24-36 hours before ovulation. This will help to identify the best two days for conception, although a woman can be fertile for a day or so before and after this time.

It is best to become familiar with your usual menstrual cycle to help figure out when you should start testing. If you have an irregular cycle then an ovulation predictor kit can help you identify the time of ovulation, but expect to use more of the test strips.

If you're trying for a baby, join BabyCentre’s supportive actively trying group to swap tips and advice with others in the same situation.

Find out more in our conception FAQs


  1. Macdonald S, Macgill-Cuerden J (2012) Mayes’ midwifery: a textbook for midwives, 14th edition, London Balliere Tindall
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Last reviewed on June 13th, 2017. Next review date June 13th, 2020.

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  • By Anonymous (not verified) on 10 Oct 2017 - 14:54

    Me and my husband have been tring to have a baby for thr past 6 months now the problem is we actually dont really have sex very often well we do but im sure not so much like peolle trying to have a baby as we both work full time... this month we had sex on our ovulation day which was the 14th day starting from my period.. some peolle have said when you start ovulation tha 8 days after is very important so you should try and have sex within that 7 days as well.. i would like some tips thank you

  • By Midwife @Tommys on 11 Oct 2017 - 14:01

    Hi, Firstly try not to worry. It can take many months before you get pregnant and this is quite normal. Have a look at our page 'Top tips to get pregnant'.
    Good luck

  • By Anonymous (not verified) on 14 Sep 2017 - 21:57

    Can I do gym while trying for baby ?

  • By Midwife @Tommys on 18 Sep 2017 - 10:20

    Being in good shape can help you conceive. The body works more efficiently when you are fit and having a toned body usually makes you feel more confident about yourself.
    Pregnancy can put a lot of strain on the body and is tiring. If you have the correct balance of muscular strength and flexibility, you can cope more easily with its demands.

    The government recommends that everyone does 30 minutes of moderate exercise five times a week.
    If you haven’t done much regular exercise before start with 15 minutes of continuous exercise three times a week.
    Then you can increase that bit by bit to 30-minute sessions four times a week and then to daily exercise. The exercise should be enough to increase your heart and breathing rates, but you should still be able to have a conversation.

  • By Anonymous (not verified) on 16 Jul 2017 - 15:06

    Can I go swimming and that when trying to get pregnant

  • By Midwife @Tommys on 17 Jul 2017 - 15:03

    Yes, there is no reason not to swim when you are trying to conceive. In fact a good exercise regime for you and your partner can help you conceive and to be in the best health for your pregnancy. Good luck

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