Fertility

Fertility: the facts

Conception, the fertilisation of a woman’s egg with sperm from a man, is a complex, delicate process. For most couples, achieving pregnancy causes no problems.

For these couples, regular unprotected sex is all it takes to conceive a child. If you’re trying for a child or thinking of doing so in the future it's good to know the fertility basics.

A woman’s monthly cycle

Every month, hormonal changes in the body cause a woman’s ovaries to release a single egg. This egg passes into the fallopian tubes, which are the tubes that link the ovaries to the uterus, or womb.

At the same time, the lining of the womb is thickening. This is to prepare it for the possibility of receiving a fertilised egg.

If the woman has unprotected sex within days of the egg being released, sperm from her male partner may fertilise her egg while it is in the fallopian tube. The fertilised egg will then travel to the womb and become embedded in its lining, where it will start to grow.

If fertilisation does not occur, the womb lining will start to break down, and will be shed through the vagina. This is the woman’s period. The period is made up of this womb lining, and a small amount of blood.

Sexually mature females have a period approximately every 28 days, though between 24 and 35 days is common.

Conceiving a child

Once an egg has been released from the ovaries, there is a 12 to 24-hour window during which it can be fertilised by sperm.

But sperm can survive in the fallopian tubes for up to 72 hours, so fertilisation could occur because of sperm that entered the fallopian tubes prior to release of the egg.

In conception, a single sperm from a man penetrates the egg of a woman. The sperm carries the father’s genes; the mother’s genes are contained in the egg. This is the moment of conception. Once the egg has been fertilised by a single sperm, no more sperm can enter.

The fertilised egg – called a zygote – continues to move down the fallopian tubes, until it reaches the uterus between three and seven days later. Here, it will implant itself into the lining of the uterus, where it begins to grow.

Up until eight weeks from the moment of conception, the implanted zygote is called an embryo. After this, it is a foetus.

For most women, the first sign that they are pregnant is a missed period. A few days after that missed period, a urine test can confirm the pregnancy. These are available through your GP or family planning clinic, and are often available at your local pharmacy.