Timing of excessive pregnancy-related weight gain and offspring adiposity at birth.

OBJECTIVE To evaluate whether the timing of excessive maternal weight gain in a cohort of women following current guidelines for healthy living during pregnancy affects neonatal adiposity at birth. METHODS One hundred seventy-two healthy women who were at least 18 years old with body mass indexes (BMIs) of at least 18.5 were recruited between 16 weeks and 20 weeks of gestation. The cohort followed healthy living guidelines during pregnancy and were retrospectively grouped according to 2009 Institute of Medicine guidelines for weight gain in the first and second halves of pregnancy: 1) appropriate gestational weight gain (ie, within Institute of Medicine recommendations) in the first and second halves of pregnancy ("overall appropriate"); 2) appropriate gestational weight gain in the first half of pregnancy and excessive gestational weight gain in the second half of pregnancy ("late excessive"); 3) excessive gestational weight gain in the first half of pregnancy and appropriate gestational weight gain in the second half of pregnancy ("early excessive"); and 4) excessive gestational weight gain throughout pregnancy ("overall excessive"). Primary measures included neonatal weight, length, BMI, and body fat at birth measured 6-18 hours after delivery. Neonatal body fat greater than 14% was considered excessive. RESULTS Neonates of women who gained excessively in the first half of pregnancy exhibited greater heel-crown length, birth weight, and excessive body fat ("early excessive" 17.5±3.1%, "overall excessive" 18.7±3.3%) compared with those born to women who gained appropriately ("overall appropriate" 13.2±4.1%; "late excessive" 14.7±3.3%; P<.01). Neonates of women who gained excessively in the first half of pregnancy had an increased risk (odds ratio [OR] 2.64, 95% confidence interval [CI] 1.35-5.17) of elevated body fat at birth compared with neonates of women with total excessive weight gain (OR 1.49, 95% CI 0.80-2.79). CONCLUSION Timing of excessive weight gain is an important factor influencing neonatal morphometrics. Prevention of early excessive weight gain should be encouraged in the period before conception and reinforced early in pregnancy. LEVEL OF EVIDENCE II.