The Patient's Guide to Embryology

How to get pregnant naturally

Men may have a constant supply of sperm, but women only release one egg every month and that egg will only live for 24 hours in the body.

Let’s start with the basics – a pregnancy happens when a sperm meets an egg, the egg gets fertilised to make an embryo and the embryo implants into the lining of the uterus around 7 days later. There are no guarantees in baby making and every couple is unique so there is no one-size-fits-all solution, some people find it very easy to get pregnant and others don’t.

How to give yourself the best chance of getting pregnant

The egg is released (ovulated) from the ovary in the middle of the menstrual cycle around 2 weeks after day 1 of your period (or more accurately 2 weeks before the first day of your next period, which is less easy to predict). To ensure the sperm gets into contact with the egg, you need to have sex around the time of ovulation. Men may have a constant supply of sperm, but women only release one egg every month and that egg will only live for 24 hours in the body. If it isn’t fertilised in these 24 hours then the egg dies and you need to wait until next month. This means that you need to have sex right around the time of ovulation to get pregnant.

Luckily sperm can live in the female body for up to 5 days to wait for the egg to be released, but your chances of success increase the closer you have sex to the day of ovulation. This is because the cervix is only open to let sperm through close to the time of ovulation and very few sperm then actually make it through the reproductive tract into the uterus’ holding area before the egg arrives.

Testing for ovulation

You can get an idea of when ovulation is approaching by testing the consistency of vaginal discharge. Stretchy and gloopy like raw egg white means ovulation, all other forms means no ovulation. Some women can literally feel the ovary release the egg with a small jolt of pain known as ‘mittelschmerz’, but neither of these methods are very reliable if you are serious about making a baby. The only way to know for sure that ovulation has occurred is by testing for a specific hormone known as luteinising hormone (LH). This can be done easily by weeing on a test strip which either gives you a yes or a no.

Do this test for ovulation every morning around the middle of your cycle, around 10 days after your period starts. As soon as you get a positive LH test, have sex. The next day, have sex again too. If your cycle is usually the same length every month you can predict more easily when ovulation is approaching and having sex before ovulation happens will increase your chance of success too.

Making a baby

If an egg has been fertilised successfully it will implant into the uterus around a week later. Once the embryo has implanted it starts to produce hCG – the hormone detected by pregnancy tests, so you can find out if you are pregnant as soon as 10 days after ovulation with an early detection pregnancy test.

A typical menstrual cycle timeline (28 day cycle)

Please remember that only a small proportion of women have a ‘typical’ cycle timeline. Any cycle length from 21 to 40 days is considered normal and it can also change each month.

This gives you an idea of when key dates happen if your cycle happens to be 28 days long:

Day 1 – This is the first day of your period

Day 9 – Fertile window opens

Day 14 – The day of ovulation

Day 15 – Fertile window closes

Day 21 – Approximately when the embryo will implant into the uterus

Days 24-26 – This will be the earliest you can do a pregnancy test

Day 28 – Period starts again if the you did not get pregnant

If you have a 29-day cycle, ovulation will be on day 15, if you have a 30-day cycle, ovulation will be on day 16 etc.

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