International standards have always assumed that women are in their reproductive years when aged between 15 and 44, and while medical technology has made it possible for some women to get pregnant in their late forties and even older, in general, these pregnancies rely on the use of donor eggs from much younger women.
Fertility in women is contingent on the age of their eggs. Peak reproductive years for women are when they are between the ages of 20 to 35, with the first seven years being the most fertile.
Many women are physically quite capable of carrying a baby well into their forties (and even fifties), but the likelihood that they are able to produce eggs that will sustain a successful pregnancy start to decline after the age of 30, becoming significantly lower each year after 35.
Between the age of 20 and the age of 27, a woman’s fertility level is at its peak.
From the age of 27 up to the age of 35, while egg quality will decline slightly as time progresses, women are still in a period of high fertility. Each year after 35, however, there is a significant decline in the quality of a woman’s eggs.