Lifestyle-induced maternal body composition changes and birthweight in overweight/obese pregnant women

Introduction: Obesity and excessive gestational weight gain (GWG) have been associated with higher occurrence of large for gestational age (LGA) babies, and several interventions have been proposed to limit GWG, which, however, does not reflect adequately the subtle changes in body composition that happens during pregnancy. The aim of this study is to evaluate if the variations of body composition, induced by a lifestyle program intended to limit GWG and measured through bioelectrical impedence analysis (BIA), could affect the newborns' weight in overweight/obese women. Methods: One hundred and thirty-nine women with BMI >= 25 kg/m(2) were enrolled between 9th-12th week and a lifestyle program, consisting of low glycemic diet with caloric restriction and physical activity, was prescribed to them. BIA was performed at enrolment and at 35th-36th week. Data regarding the newborns' weight were collected from clinical charts after delivery. Results: Women who exceeded recommended range of GWG had an higher occurrence of LGA babies. Analysing the body composition, fat free mass (FFM) showed a direct correlation with the birthweight centile, even after correcting for BMI at enrolment, age and gestational diabetes mellitus. Interestingly, women who had an increase in fat mass (FM) and visceral FM throughout pregnancy had an higher occurrence of small for gestational age (SGA) babies. Conclusion: The increase in FM and visceral FM during pregnancy in overweight/obese women is linked to a higher occurrence of SGA babies.