The effects of female age on fecundity and pregnancy outcome.

In industrialized countries worldwide, women are delaying childbearing for a variety of reasons, including pursuit of career, greater financial independence, improved and more accessible contraception and longer life expectancy. In terms of fertility and maternity, those aged > or = 35 years are considered to be of advanced maternal age and there are usually marked reductions in both the fecundity rate for spontaneous conceptions and the success rates with assisted conception. These decreases are thought to be due mainly to oocyte ageing, and the established success of oocyte donation from younger individuals to older recipients supports this contention. For those who achieve a pregnancy at an advanced maternal age there is a greater likelihood of aneuploidy (assuming conception with the woman's own oocytes), hypertensive and other medical disorders, birth by Caesarean section and maternal mortality. However, most of the complications associated with advanced maternal age are caused by age-related confounding variables, and older premenopausal women in good health should not require special attention. The data on perinatal mortality rates are encouraging and in the absence of congenital abnormalities perinatal mortality is probably not much increased, if at all, in older mothers. Pregnancy is now possible for postmenopausal women with the application of oocyte donation, but these individuals have a significantly higher likelihood of cardiovascular ageing and should be considered at increased risk of vascular complications during pregnancy.