Toward a better understanding of the "advanced maternal age" factor.

Women over the age of 30-35 are presumed to encounter more adverse pregnancy outcomes because of their reduced reproductive efficiency. In the vast majority of studies of advanced maternal age and pregnancy outcome, however, researchers have failed to control for important contextual differences surrounding the pregnancy and childbirth experiences of younger and older women. These contextual differences can account for a considerable portion of the differential results mistakenly ascribed to reproductive age. In this article are reviewed research findings that identify three such hidden factors: older women's increasing likelihood of chronic diseases that adversely affect pregnancy outcome; the altered medical management of middle-aged women's pregnancies and labors, with resultant iatrogenically caused complications; and demographic characteristics suggesting that midlife pregnancy in the past has been associated with poverty or subfertility and today is associated with healthy middle-class postponers.