A woman is born with all the eggs that she will ever have in her life. The eggs age with it, decreasing both in quality and quantity. Age is the single most important factor affecting the fertility of a woman. Although good health increases the chances of getting pregnant and having a healthy baby, it doesn’t rule out the effect of age on a woman’s fertility.
A woman in her early to mid 20s has a 25–30% chance of getting pregnant every month. Fertility generally begins to diminish when a woman is in her early 30s, and even more so after the age of 35. At 40, the chance of getting pregnant in each monthly cycle is about 5%.
Fertility changes as you age. Both men and women become fertile in adolescence after puberty. For girls, the start of their reproductive year is marked by the onset of ovulation and menstruation. It is generally understood that after menopause women are no longer able to get pregnant. Generally, reproductive potential declines as women age, and fertility is expected to end 5 to 10 years before menopause.
The best reproductive years for a woman are in her 20s. Fertility gradually declines in your 30s, especially after 35 years of age. For every month she tried, a healthy, fertile 30-year-old woman had a 20% chance of getting pregnant. That is, for every 100 women of childbearing age 30 who try to conceive in one cycle, 20 will succeed and 80 will have to try again. By the age of 40, a woman’s chances are less than 5% per cycle, so less than 5 out of every 100 women are expected to succeed each month.
Because of the changes that occur in eggs and sperm with age, including damage to genetic material, children of older parents are at a slightly higher risk of birth defects and genetic disorders. The risk of mental health problems and autism spectrum disorders is slightly higher in children of fathers older than 40 years than in those with younger fathers.
It is estimated that the risk of having a baby with a chromosomal (or genetic) abnormality is about one in 400 for a woman over 30 and one in 100 for a woman over 40.
The risk of miscarriage and complications in pregnancy and delivery is higher in older women than in younger women.
Older women also have a higher risk of developing gestational diabetes, placenta previa, placental abruption, stillbirth and caesarean delivery than younger women.
