The influence of body weight on reproductive function in women.

Abstract

SUMMARY The influence of weight on reproductive function is examined in a representative group of fertile women for whom data were recorded during pregnancy and for 2 years after delivery. The indices used were (a) the weight at the first antenatal examination (adjusted according to the number of days by which it preceded or followed the 124th day of gestation), and (b) an index of body build derived from the observed regression of the adjusted antenatal weight on height. Menstruation was recorded during the 12 months after delivery. Mean duration of postpartum amenorrhoea (Table 1) and mean cycle length (Tables 4–6) decreased with increasing body weight and with increasing degree of obesity. The incidence of menstrual irregularity appears to be unrelated to both indices (Table 3). Duration of gestation (Table 7), of labour (Table 8) and of lactation (Table 10), and the incidence of abortions, stillbirths and infant deaths in previous pregnancies (Table 9) were not consistently related to weight or body build. Birth weight of offspring increased with increasing degree of maternal obesity (Table 13) and was more closely associated with maternal weight than with maternal height (Table 11). The coefficient of correlation between birth weight and mother's weight (corrected for mother's height) is 0·20, and between birth weight and mother's height (corrected for mother's weight) is 0·09 (Table 12). It is concluded that the only evidence of variation with increasing degree of obesity in these features of reproductive function in a group of fertile women is a slight increase in frequency of menstruation and an increase in birth weight of offspring. The relation between weight and fertility was not examined and will be considered in a later communication.