Relación entre el índice de masa corporal durante la gestación en embarazadas adolescentes y adultas, indicadores antropométricos de crecimiento fetal y retardo de crecimiento intrauterino. La Costa, Argentina, 1999

Body mass index (BMI) has been employed as an epidemiologic predictor of fetal growth. But most of the studies are focused on BMI values for non pregnancy women, while BMI varies according to gestational age. On the otherhand, adolescence has been considered as a risk factor for intrauterine growth retardation (IUGR :birthweight for gestational age < 10 t h . centile). The aims of this study were: 1) to identify the distribution for weight, height and BMI in adolescent and adult pregnancies, 2) to measure the association between maternal BMI and fetal growth and 3) to evaluate the relative risk to have an intrauterine growth retardation (IUGR) according to maternal BMI. 2409 pregnancies and their newborns were studied. Maternal height and weight were measured and BMI by gestational age was calculated by trimesters of gestation . Birthweight, recumbent lenght, cefalic perimeter, BMI and weight by gestational age were determinied in the newborns. Z score by gestational age were calculated in each pregnant woman taken into account the cutt of point of BMI of - 1 standard deviation. There were highly statistically significants differences in both body size and body composition between adolescent and adult mothers and in their newborns. The newborns from mothers with BMI under -1 standard deviation were smaller and the relative risk to have an IUGR was double for newborns whose mothers had BMI under - 1 standard deviation. Conclusions: 1- Both body size and composition values differs between newborns from mothers under or above the cut off point of -1SD of BMI and 2- The risk to have an IUGR was double in pregnancies under -1 SD of BMI, independently to the age of the mother.