As every unattached woman in her twenties or thirties out there is well aware, the most important factor determining her chance of achieving pregnancy is age. In broad terms, fertility starts to decline when women are in their early 30s, the rate of decline speeds up at around age 35 and by age 40 and beyond, the chance of pregnancy is slim and the risk of miscarriage high. This is because, as women age, the quantity and quality of their eggs decrease.
Menopause marks the absolute end of the reproductive lifespan. The age of menopause varies between women but usually occurs between the ages of 45 and 55 years. Pregnancies in the ten years leading to menopause are rare.
The age at which women are having their first baby is increasing in Australia and elsewhere. This in turn increases the risk of age-related infertility. Women who worry about their “biological clock” ticking away, particularly single women, want to know how long they can wait without jeopardising their chance of having a baby.
Can women tell how long they have?
Women are increasingly having the so-called “egg timer” test to get an idea of how much longer they have to achieve pregnancy. The authors of a recent Australian study recommend women in their late 20s have the “egg timer” test at regular intervals to monitor their fertility potential.
This is a blood test that measures a woman’s level of anti-müllerian hormone (AMH) which is linked to the number of eggs remaining in a her ovaries. Higher levels mean more eggs are present, which theoretically means a higher fertility potential.
But the “egg timer” test does not provide information about the quality of the eggs, which mostly depends on a woman’s age.
Relying on the “egg timer” test for pregnancy planning can give women with normal or high readings a false sense of security about postponing childbearing and women with low readings unnecessary worry about their ability to have children. This might lead them to pay the significant cost associated with egg freezing.
1 in 6 Aussie couples are affected by infertility. Here’s a handy fertility guide to get you started.