Relation between age and fertility

We’re born with a pre-determined number of eggs in our ovaries – around one million – and by puberty the reserve is down by half that amount. You’ll release around 400 eggs during her lifetime, which if not fertilized, will become your monthly period. At roughly age 35 the quality of your eggs declines dramatically.

In your teens Teenagers who don’t use contraception have a 90 percent chance of conceiving in the first year, but are more likely to experience complications such as pre-eclampsia if they fall pregnant.

In your twenties You’ll release your best eggs in your twenties and they’ll give you a 90 percent chance of conceiving within a year. Your risk of having a baby with Down syndrome or other chromosomal abnormalities is 1 in 1500.

In your thirties Fertility declines sharply after you’re 35, and the risk of having a baby with chromosomal abnormalities increases. Women in their thirties and forties are likely to have a healthy baby but they do face more complications. The risk of bearing a child with chromosomal abnormalities such as Down syndrome increases as you age. The rate of miscarriage in women who are older is also significantly greater (this is likely linked to chromosomal abnormalities). While women aged over 35 have more difficulty conceiving, they also have more chance of having twins, as the likelihood of naturally conceiving twins peaks between the ages of 35 and 39 (see also expecting triplets).

All these facts may seem daunting but it is worth remembering that since the late 1970s, birth rates for women in their late thirties and forties have increased dramatically. As long as your overall health is good, there is no reason why you can’t continue to have babies well into your forties. For a man, although the quality of his sperm may go down, he can still conceive a healthy child well into his eighties and nineties. The general rule of thumb is, if conception hasn’t taken place after six months of trying, women aged over 35 should consult a fertility specialist.

In your forties You have a 31 percent chance of conceiving naturally but you’re at a greater risk of having miscarriages, children with chromosomal abnormalities and twin or multiple births.

You can work out your most fertile time over the next 12 months by using our ovulation calculator. Do you want to talk to other moms about trying for a baby? Visit our trying for a baby chat forum or answers area.

The information in this feature is intended for educational purposes only. If you have any concerns about your health, the health of your child or the health of someone you know, please consult with a doctor or other healthcare professional.

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Last Modified: 02/05/2007

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