Prenatal weight gain and the birthweight of triplets. 
The objective of this study was to evaluate the association between maternal factors, including rates of gestational weight gain before and after 24 weeks' gestation, and adequacy of intrauterine growth for gestational age at birth of triplets, as a mean Z-score of the triplet set.  The study design was a retrospective, anonymous, pilot telephone survey of mothers of triplets and an historical cohort analysis of their prenatal weight gain records.  The statistical analyses performed included multiple regression analysis to formulate a model for mean triplet Z-score (a measure of birthweight-for-gestational age) and analysis of variance to confirm and simplify the components of this model.  Factors significant in the final model and their beta coefficients included weeks' gestation (-0.124, p < 0.0001), rate of gain before 24 weeks' gestation (0.606, p = 0.005), and induced conception (-0.404, p = 0.01).  Rate of gain > or = 1.5 lbs/week before 24 weeks was significant in the analysis of variance (p = 0.009).  Better intrauterine growth for gestational age is achieved in triplet gestations with maternal weight gains of > or = 1.5 lbs/week before 24 weeks' gestation.