Has fecundability been declining in recent years in developed countries? A comment.

Abstract

2 objections may be lodged against James (1981) who offers evidence that Western fecundability has been declining. His argument, together with the author's previous comment, engenders concern about the effect of technological change on reproductive ability. The recent fertility decline was, with minor exceptions, characterized by an increasing concentration of childbearing in the younger age groups. The age shift continues that observed in essentially every Western fertility decline thus far, and it is regarded as proof of increasing family limitation. Secondly, changes in reproductive potential cannot greatly affect reproduction unless the affected population is reproducing near that potential. A fecundity decline could not then effect the recent decline in fertility unless Western fecundity in 1960 had already been unexpectedly low. James offered his effect as only a partial explanation of that fertility decline. Before accepting such a concession, it is necessary to question whether the explanations and procedures of demography give reason to reject a biosocial explanation of the overall Western fertility decline, particularly one based on an increasing prevalence of degenerative diseases. Several objections to such a "demographic degeneration" theory are impugned by ambiguities in the usual demographic definitions of fecundity and birth control. The Davis-Blake framework for fertility analysis and the many surveys based on it fail to consider reasonable distinctions between the social and biological motives for birth control and between voluntary family limitation and behavioral disorders affecting fertility. As yet, the predicted sociopsychological determinants of fertility have not been found. Many demographers now concede the inadequacy of the desired family size model of childbearing. Couples reproductively compensate for child deaths at barely 1/4 of the rate it predicts. Social demographers have overlooked data providing 2 independent corroborations of a degeneration theory: the increase in chronic diseases affecting Western populations has been characterized by the same shift in age patterns as the Western fertility decline--both most affect the oldest ages; and the fertility declines experienced by animals subjected to several continuous stresses are accompanied by that same shift in the age pattern. These considerations suggest that James' effect may be a major component of an explanation based on increasing chronic disease, subfecundity, health motivated family limitation, and behavioral disorders affecting fertility.