Sterility increases with age

For women, the risk of being unable to have a baby (without medical assistance) increases with age. At age 25 it is around 5 %, but increases to 10 % at age 30, 20 % at age 35 and 40 % at age 40. In some cases, women are able to conceive but the pregnancy does not result in a live birth.

The causes of this decline in fecundity with age are still largely unknown. The degeneration of women's reproductive functions from age 35-40 is an important factor, as are sexually transmitted diseases such as gonorrhoea and chlamydia which are known to cause sterility. Some causes, such as severe genetic abnormalities in the foetus, are unpreventable. But the simple fact that sexual activity slows down with age should also be taken into account!
Moreover, sterility is not an exclusively feminine problem, and in 40 % of cases the problem lies with the man. Sometimes, neither member of a couple is sterile: each could have children with a different partner, but together they cannot conceive. This is known as couple infertility.

To find out more:
"Causes et traitements de la stérilité" (H. Léridon, in Démographie, analyse et synthèse, volume II, 2002, page 255)
"Can assisted reproduction technology compensate for the natural decline in fertility with age ? A model assessment" (H. Léridon. Human reproduction, 19 (7), p. 1549-1554, 2004)