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Fertility health centre

Fertility basics

Conception takes place when a woman's egg gets fertilised by a man's sperm resulting in pregnancy.

Pregnancy happens after unprotected sex or a problem with a method of contraception.

Getting facts on fertility can help for couples 'trying' for a baby.

A woman's monthly cycle involves hormonal changes telling the ovaries to release an egg.

The egg travels down the fallopian tubes from the ovaries to the womb (uterus). The womb lining becomes thicker in readiness for an egg being fertilised in the fallopian tube. If there's no fertilisation that month, the womb lining and some blood is removed though the period. The monthly cycle lasts around 28 days. The first sign of a pregnancy is usually a missed period.

An egg may be fertilised by sperm within 12 to 24 hours of being released. Because sperm itself can survive for up to 7 days inside a woman, fertilisation can happen even if a couple had sex before the egg was released.

Genes from the dad are in the one sperm that fertilises the egg. Genes from the mum are in the egg, which once fertilised is known as a zygote.

The zygote reaches the uterus around three to seven days after fertilisation. Once implanted to the wall of the uterus, it starts growing.

The next milestone for the zygote comes eight weeks after the conception, when it becomes known as a foetus.

If a woman thinks she may be pregnant, a pregnancy test of her urine done several days after a missed period (and sometimes even before she misses a period) can confirm it. Test kits can be bought from pharmacies or can be obtained through GP surgeries, sexual health clinics, and family planning clinics.

There are steps to take before planning a pregnancy, including taking folic acid and vitamin D supplements, and talking to your GP about any lifestyle changes – such as achieving a healthy weight and quitting smoking.


For most couples, having a baby is straightforward - by having regular and unprotected sex.

Around 85% of couples conceive naturally within a year

However, one in six or seven couples in the UK has difficulty conceiving.

My partner and I are having trouble conceiving. What could be the problem?

Infertility can be due to problems in the man, the woman, a combination of both partners, or in some cases, no identified reason. Having no reason found can be as high as 30% for women.

A couple will be diagnosed as infertile if they have not had a baby after trying for two years.

Infertility may be classified as:

Primary infertility, where someone who has not conceived a child before has difficulty conceiving

Secondary infertility, where a person has had a pregnancy or pregnancies in the past, but is now having difficulty conceiving.

WebMD Medical Reference

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