Do you know how to tell when you're ovulating? Or exactly how many days there are in your cycle when you could get pregnant? Will the method of contraception you've been using make a difference to how quickly you conceive? And how long should it take before you get a positive pregnancy test?
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| Pregnancy And Infertility |
The female reproductive system is complex, and getting pregnant involves a linked chain of events in a woman's body, which begin long before the act of sexual intercourse. A minor imbalance anywhere along the line can cause major problems, and when you look more closely at what has to happen to make a baby, it starts to seem quite incredible that so many women manage to get pregnant without any problem.
Basic terms
It may be helpful to start by looking at the different parts of the female reproductive system, and the role they play in our fertility.
Eggs and ovaries
The word ovary comes from the Latin ovum, or egg, and we store our lifetime's supply of eggs in our ovaries. Women have two ovaries, one on either side of their womb, situated just behind it. Each ovary is about the size of a walnut, and the eggs inside are so tiny that they are invisible to the human eye.
Women begin making eggs before they are born. The process starts in the mother's womb when a female embryo is still smaller than a grain of rice, less than a month after fertilization. By the time a baby girl has been in her mother's womb for five months, her ovaries contain several million eggs, the most they will ever hold. From this point onwards, eggs begin to perish, and by the time a girl is born about half the eggs in her ovaries will have died. This process will carry on throughout her life, and at puberty a girl has half a million eggs at most left in her ovaries. Of these, only four or five hundred will ever mature and have the potential to be fertilized, and the average woman will see fewer than three of them grow into children during her lifetime,
A female's ovaries cannot produce any more eggs once she is born. This means that unlike men, who carry on producing fresh sperm into old age, women are governed by their biological clocks. Towards the end of her reproductive life, a woman is releasing eggs that have been in her body for more than 40 years. She becomes less and less fertile until eventually she stops ovulating (releasing ripe eggs) altogether, sometime between her mid forties and late fifties.
The womb
The uterus, or womb, is the size and shape of an upside down pear with thick, muscular walls. It is here that a fertilized egg will implant itself and grow, and the womb can stretch to accommodate a growing baby. The womb grows a special soft, spongy lining every month to create the right environment for a fertilized egg to implant, and if this doesn't happen the lining is shed in your period.
The fallopian tubes
Leading from each ovary into the womb are two tiny paths called the fallopian tubes. They are around 10cm (4in) long, and about the thickness of a pin. The end of the tube closest to the ovary has a fluted, funnel shape and is edged with fimbria - delicate fingers that gather up the egg and send it on the journey down the tube. The tube is lined with tiny hair-like cilia that help the egg move towards the womb.
The hypothalamus and pituitary gland
The hypothalamus is a gland in the centre of the brain, and the pituitary gland is situated beneath it at the base of the brain. Together the hypothalamus and pituitary glands orchestrate the production of the hormones that tell the woman's reproductive organs what to do and when to do it. To find out more, you can check out Pregnancy And Infertility.
