Maternal pelvic size, measured by dual energy X-ray absorptiometry, predicts infant birthweight.

Indicators of infant birthweight are important because infant birthweight is related to later health outcomes. This study developed and validated new measures of the pelvis from dual energy absorptiometry (DEXA). Predictors of the new measures of maternal pelvic size were examined and the pelvic size measures were examined as predictors of infant birthweight. Data were drawn from a sample of 326 women in Hawaii and their 608 infants. The women were 45-60 years old at the time of the DEXA bone scan and when they recalled the birthweights of their infants. The birthweights were validated with birth certificate data. The women were participants in the Early Postmenopausal Interventional Cohort (EPIC) to study the effects of alendronate on bone density. Questions on birth histories were added to that study. Adolescent milk consumption and age at menarche were positively associated with the DEXA hip measure, while Asian ethnicity was negatively associated with the hip measure in multiple regression analysis. In multiple regression analysis, the hip measure, together with infant gender and gestational age predicted infant birthweight; mother's height, weight, and ethnicity did not add significantly to the model. DEXA provided measures of the pelvis, which varied by ethnicity, hormonal and nutritional variables, and which were indicators of infant birthweight. Am. J. Hum. Biol. 12:552-557, 2000. Copyright 2000 Wiley-Liss, Inc.