Fetal femur length is influenced by maternal dairy intake in pregnant African American adolescents.

BACKGROUND Pregnant adolescents may compete with their developing fetuses for the nutrients required for optimal bone mineralization. OBJECTIVE The objective of this study was to determine the effect in pregnant African American adolescents of maternal dairy intake at entry into prenatal care on fetal femur development between 20 and 34 wk of gestation. DESIGN A 10-y retrospective chart review was carried out in 1120 pregnant African American adolescents (<or= 17 y of age) who had received care at an inner-city maternity clinic between 1990 and 2000. Generalized multiple linear regression models were used to address significant determinants of fetal femur length after control for gestational age, biparietal diameter, maternal age and height, and prepregnancy body mass index. Dairy intake was estimated at entry into prenatal care on the basis of 24-h dietary recall and a food-frequency questionnaire. Data from 350 subjects, for whom data on all variables were available, were included in the model. RESULTS In these pregnant adolescents with a mean (+/- SD) age of 15.9 +/- 1.1 y (range: 12.7-17.9 y), dairy intake had a significant positive effect on fetal femur growth after adjustment for gestational age, biparietal diameter, maternal age and height, and prepregnancy body mass index (P = 0.001, R(2) = 0.97). Fetal femur length was significantly lower in the lowest dairy-intake group (< 2 servings/d) than in the highest dairy-intake group (> 3 servings/d), and a dose-response relation was suggested in the intermediate dairy-intake group (2-3 servings/d; P = 0.089). CONCLUSION These data suggest that consumption of < 2 servings of dairy products/d by pregnant adolescents may negatively affect fetal bone development by limiting the amount of calcium provided to the fetus.