How does age affect your fertility?

Many women these days are leaving it later than ever to have children. In the past, couples typically started families in their early twenties, whereas now many wait until their thirties or forties to get pregnant.
Women over 35 are slightly more at risk of complications but the vast majority can expect an uncomplicated pregnancy and a healthy baby.  The most common problem faced by women in this age group can be getting pregnant in the first place, as fertility decreases with age.

When are women most fertile?

A woman is at her most fertile somewhere between about 18 and 24. After the age of 35, a woman’s fertility starts to decrease quite rapidly.

About 94% of women aged 35 will conceive after trying for three years. This drops down to 77% by the time you reach 38 years.

What factors affect fertility as you get older?

The main age-related issues affecting your fertility are the quantity and quality of your eggs. You are born with all the eggs you will ever produce – up to two million of them. By the time a woman hits puberty this number has dropped to between 300,000 and 400,000.

During each menstrual cycle only one or two of the 20 or so eggs the ovaries have prepared will go on to become mature eggs. These are known as ‘good’ eggs, which are able to be fertilised and will develop into a healthy pregnancy. As you get older, the number of ‘good’ eggs will naturally decline. You will also be more prone to irregular or shorter periods, which can make it more difficult to get pregnant.

The lining of the uterus can become thinner too, making it harder for a fertilised egg to embed itself and become a viable pregnancy.

If you are over 35, it’s worth getting advice from your doctor as soon as you think you may have trouble conceiving, so that any problems can be spotted in good time.

What are the risks for mother and baby if you are over 35?

The good news is that you are not more at risk of major complications with either the pregnancy or the birth than younger women. However, there are some age-related risks;

Older women are more likely to develop gestational diabetes. Your doctor can advise you on diet to help prevent serious problems.

Women over 35 are at greater risk of having a baby with Down’s syndrome, a genetic condition which can affect cognitive and physical growth. The chances rise from one in 2000 for a woman in her twenties to one in 100 for a woman of 40. You will be offered screening for this condition and counseling and advice if you are thought to be carrying a Down’s baby.

Older mums have a slightly higher risk of miscarriage and stillbirth but do remember that stillbirths are still extremely rare.

Older women are more at risk of high blood pressure, which can lead to pre-eclampsia but you will be monitored throughout your pregnancy.

Babies born to mums over 35 are slightly more prone to premature birth or low birth weight.

The rates of induction, caesarean and assisted births (with forceps or ventouse) are also slightly higher for older women.