Body mass index--specific weight gains associated with optimal birth weights in twin pregnancies.
OBJECTIVE
To formulate maternal weight gain guidelines, by maternal pregravid body mass index (BMI) status, associated with optimal fetal growth and birth weight in twins.


METHODS
This historical cohort study was based on 2,324 pregnancies with nonanomalous, liveborn twins (4,684 infants) from Ann Arbor, Charleston, Baltimore and Miami. Rates of maternal weight gain and fetal growth were modeled using multiple regression for 0-20 weeks, 20-28 weeks and 28-38 weeks (projected as necessary), controlling for potentially confounding factors. Optimal rates of fetal growth were defined as growth between the singleton and twin 50th percentiles, and optimal birth weights were defined as between the singleton 50th percentile and twin 90th percentile at > or = 36 weeks (2,850-2,950 g).


RESULTS
Optimal rates of fetal growth and birth weights were associated with rates of maternal weight gain for underweight women of 1.25-1.75 lb/wk (0.57-0.79 kg/wk) to 20 weeks, 1.50-1.75 lb/wk (0.68-0.79 kg/wk) between 20 and 28 weeks and 1.25 lb/wk (0.57 kg/wk) from 28 weeks to delivery; for normal-weight women, 1-1.5 lb/wk (0.45-0.68 kg/wk) to 20 weeks, 1.25-1.75 lb/wk (0.57-0.79 kg/wk) between 20 and 28 weeks and 1.0 lb/wk (0.45 kg/wk) from 28 weeks to delivery; for overweight women, 1-1.25 lb/wk (0.45-0.57 kg/wk) to 20 weeks, 1-1.5 lb/wk (0.45-0.68 kg/wk) between 20 and 28 weeks and 1 lb/wk (0.45 kg/wk) from 28 weeks to delivery; for obese women, 0.75-1 lb/wk (0.34-0.45 kg/wk) to 20 weeks, 0.75-1.25 lb/wk (0.34-0.57 kg/wk) between 20 and 28 weeks and 0.75 lb/wk (0.34 kg/wk) from 28 weeks to delivery.


CONCLUSIONS
Optimal rates of fetal growth and birth weights in twins are achieved at rates of maternal weight gain that vary by period of gestation and maternal pregravid BMI status.
Department of Epidemiology and Public Health, University of Miami School of Medicine, 1801 NW 9th Avenue, Room 200H, Miami, FL 33136, USA. bluke@med.miami.edu
Barbara
B
Luke
Mary L
ML
Hediger
Clark
C
Nugent
Roger B
RB
Newman
Jill G
JG
Mauldin
Frank R
FR
Witter
Mary Jo
MJ
O'Sullivan
D000328:Adult; D001724:Birth Weight; D015992:Body Mass Index; D015331:Cohort Studies; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D020567:Fetal Weight; D005865:Gestational Age; D017408:Guidelines as Topic; D006801:Humans; D007231:Infant, Newborn; D009751:Nutritional Requirements; D009765:Obesity / Q000517:prevention & control*; D011247:Pregnancy; D011272:Pregnancy, Multiple; D012016:Reference Values; D014427:Twins; D015430:Weight Gain