Spontaneous fetal loss: a note on rates and some implications

Abstract

SummaryAfter reviewing recent work indicating that the level of spontaneous fetal loss (SFL) is much higher than estimates derived from traditional sources, this paper assesses some implications of differential rates of SFL by race and maternal health and challenges the common view that early SFL is largely a function of genetic abnormalities of the fetus and thus subject to little change over time. If, as is argued here, SFL changes over time in response to changing environmental conditions, fertility trends may be affected by environmental trends. An example of the possible impact of declining SFL on marital fertility rates over the period 1940–60 in the US is provided. The paper concludes with work that uses new estimates of SFL rates to measure the extent to which induced abortion may be unnecessary because the pregnancy would terminate spontaneously, and then estimates the extent to which contraceptive failure rates, as measured in the US National Fertility Study of 1965, may be deflated due to under-reporting of SFL.