Working out your cycle length

There is a simple calculation you can use to get an idea of when your fertile time might be. You will need to know the length of your last 6 to 12 menstrual cycles.

Say, for example, your cycle lengths were 25, 30, 27, 31, 28, and 32 days, your shortest cycle is 25 days and your longest cycle is 32 days. Subtract 20 days from your shortest cycle and 10 days from your longest cycle.

25 to 20 = 5
32 to 10 = 22

This would mean that your potential fertile time would start on day five and would last until day 22. This gives a very rough guide to your estimated fertile time. The changes in cervical secretions reflect changes in your hormone levels and give the best sign of what is happening in your body on a day to day basis.

Ovulation

Cervical mucus changes
The cervix secretes mucus throughout the menstrual cycle, starting off sticky white and gradually changing to thinner, clearer mucus.

As your body gets ready for ovulation and during ovulation, the mucus increases and becomes much thinner, slippery and stretchy. If you were to put some between your finger and thumb, you would find that it may stretch several centimetres. 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.

To boost your chances of conceiving aim to have sex every couple of days throughout your cycle so you know that there are hopefully sperm waiting for the time that the egg is released. This also helps to keep the sperm in good quality. If you are quite sure when you ovulate each month some women choose to make love in the days leading up to ovulation. Continue having sex for three days after your peak day (as this allows time for ovulation and the lifespan of the egg). After this your fertile time will be over for that cycle.

Temperature
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 give you any indication of when your fertile time starts, this is not a useful indicator for most women. Looking at your cervical mucus changes is a more useful indicator as it tells you when the conditions are optimum in your body to help the sperm to survive and wait for an egg to be released.

Using ovulation kits
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.

We recommend regular sex throughout the cycle as the way to maximise your chances of conception. However, some couples find ovulation predictor kits helpful.

Top tips for planning a pregnancy

1.      Start taking folic acid now. This will help to prevent spina bifida and you should take a 400mcg tablet each day until you are at least 12 weeks pregnant. A great way to get your folic acid intake and to plug any other gaps in your diet is to take Tommy's multi-vitamins, which are specially designed for pregnant women and those looking to conceive. They are available in Boots or you can buy them online.

2.      Keep a diary of your menstrual cycle. Some women know to the day when their period will start but for many women their cycles are much less predictable. Make a note of your periods. This will give you a good indication of how long your cycle is and you can work out when you might be ovulating.

3.      Give your body time to adjust. If you’ve stopped taking hormone contraceptives, don’t worry if your periods are irregular for the first few months – your body is still adjusting to the change in hormone levels.

4.      Go for a check up. Check with your doctor that you have rubella immunity. This infection can cause serious harm to your unborn baby.

Seeking help with fertility

If you find that either of you are becoming stressed because you haven’t conceived yet, then make an appointment sooner. Worrying about conceiving is perfectly normal but getting stressed can seriously hinder your chances.

Find out about male fertility