Early weight gain does not decrease the incidence of low birth weight and small for gestational age triplets in mothers with normal pre-gestational body mass index

Objective: To examine if the recommended weight gain of >680 g/week during the first 24 weeks of pregnancy decreases the frequency of adverse birth weight outcomes in triplet mothers with a normal pregravid BMI. Study design: Retrospective observational study of a large sample of triplet mothers with a normal (19.8-26) pregravid BMI. Adequate, average, and inadequate weight gains were defined as >680, 500-680, and <500 g/week. Outcome measures were the incidence of ≥1 SGA infant and total triplet birth weight <4500 g. Results: Of the 1166 triplet mothers, 208 (17.8%) gained >680 g/week during their pregnancy. This presumed adequate weight gain did not reduce the incidence of SGA triplets or that of total birth weight <4500 g, irrespective of parity. These adverse birth weight outcomes were 2 to 3.5 times lower among multiparous compared to nulliparous mothers. Conclusion: Early weight gain of >680 g/week in triplet mothers with a normal pre-pregnancy BMI is not associated with a decrease in the incidence of adverse outcomes. Weight gain recommendations in triplet pregnancies should be realistic and associated with a low risk-benefit ratio.