The Influence of Reproduction on Body Weight in Women

SUMMARY 1. Data recorded in respect of all women whose children were born in a county borough during one year included 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 at 3, 6, 9, 12 and 24 months after delivery. The present communication is concerned with the influence of reproduction on body weight. 2. It is estimated that between conception and 24 months after birth women gained, on the average, approximately 6·6 lb. This is about 5 lb. more than would have been added in the same period if they had not been pregnant. Reasons are given for believing that these estimates may be a little low, probably not by more than 1 lb. 3. The increase in weight occurred mainly during pregnancy. From 3 months after delivery changes in mean weight were relatively small: a loss of 1·8 lb. between 3 and 12 months, and a gain of 0·6 lb. between 12 and 24 months. 4. The increment in mean weight between conception and 24 months increased slightly with parity, and, less certainly, with age. The most striking association with these variables occurred between 3 and 12 months after birth, when the proportion of women who gained weight decreased with increasing parity and increased with increasing age (Fig. 5). It is suggested that this relationship is probably attributable to an association between age and parity and social circumstances, and it is shown that the same trend was exhibited by the growth rates of the offspring of the same mothers during the first year of life (Fig. 6). 5. Lactation had little influence on mean weight. It resulted in a small loss during the period of lactation, but its effect was almost eliminated at 24 months after delivery (Fig. 7). 6. During the various intervals between early pregnancy and 24 months after delivery weight changes appear to be continuously distributed (Fig. 1). The constants of the distributions are given (Table 4).