Age affects the ability to conceive and have a healthy baby. Age is the single biggest factor affecting a woman’s fertility. For men, age-related fertility decline is more subtle but does happen.
Women’s age and fertility
A woman is born with all the eggs she is going to have in her lifetime. Her eggs age with her, decreasing in quality and quantity. This is why age is the single most important factor affecting a woman’s fertility. While good health improves the chance of getting pregnant and having a healthy baby, it does not override the effects of age on a woman’s fertility.
In her early to mid-20s, a woman has a 25 to 30 per cent chance of getting pregnant every month. Female fertility generally starts to decline when a woman is in her early 30s, and the decline speeds up after the age of 35. By age 40, the chance of getting pregnant in any monthly cycle is down to around five per cent.
It is a common misconception that IVF treatment
can overcome age-related infertility. A woman’s age also affects the chance of success with IVF. The chance of a live birth resulting from one IVF cycle for women of different ages in 2014 in Australia and New Zealand is illustrated.
For older women the chance of having a baby increases if they use eggs donated by a younger woman.
The risk of pregnancy complications increases with age too. The risk of miscarriage and chromosomal abnormalities in the fetus increase significantly from age 35. Complications such as gestational diabetes, placenta previa (when the placenta covers all or part of the cervix, which increases the risk that the placenta will detach), caesarean section, and still birth are also more common among older than younger women.
Men’s age and fertility
While the effects of female age on fertility have been known for a long time, more recent studies have found that the age of the male partner also affects the chance of pregnancy and pregnancy health.
Male fertility generally starts to decline around age 40–45 years when sperm quality decreases. Increasing male age reduces the overall chances of pregnancy and increases time to pregnancy (the number of menstrual cycles it takes to become pregnant) and the risk of miscarriage and fetal death.
Children of older fathers also have an increased risk of mental health problems (although this is still rare). Children of fathers aged 40 or over are five times more likely to develop an autism spectrum disorder than children of fathers aged 30 or less. They also have a slightly increased risk of developing schizophrenia and other mental health disorders later in life.
This page has been produced in consultation with and approved by:
Victorian Assisted Reproductive Treatment Authority
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