Each year, out of every 1000 pregnant women over the age of 35, 994 have healthy pregnancies. Most of the complications associated with later childbearing reflect chronic conditions that accompany aging, such as hypertension and diabetes, which can complicate an otherwise healthy pregnancy. These complications often result in the need for cesarean delivery, which can complicate an otherwise healthy pregnancy. These complications often result in the need for cesarean delivery, which is twice as common in pregnant women over the age of 35 as among younger women. For all these reasons, maternal mortality rates are higher in women over 35 than in younger women.
Infants of older mothers face problems of their own. Birth defects, preterm births, growth retardation, and death are common among infants born to women over 35. Because 1 out of 50 pregnancies in older women produces an infant with genetic abnormalities, obstetricians routinely screen women older than 35. For a 40-year-old mother, the risk of having a child with Down syndrome, for example, is about 1 in 300 for a 35-year-old and 1 in 10,000 for a 20-year-old. Fetal mortality is twice as high for women 35 years and older than for younger women. Simply being older seems to carry a risk of its own. One possibility is that the uterine blood vessels of older women cannot fully adapt to the increased demands of pregnancy.