A systematic review of outcomes of maternal weight gain according to the Institute of Medicine recommendations: birthweight, fetal growth, and postpartum weight retention.

This systematic review focuses on outcomes of gestational weight gain, specifically birthweight, fetal growth, and postpartum weight retention, for singleton pregnancies with respect to the 1990 Institute of Medicine weight gain recommendations. A total of 35 studies met the inclusion criteria and were reviewed. There was strong evidence to support associations between excessive gestational weight gain and increased birthweight and fetal growth (large for gestational age) as well as inadequate gestational weight gain and decreased birthweight and fetal growth (small for gestational age). There was moderate evidence to support the association between excessive gestational weight gain and postpartum weight retention. Clear clinical recommendations based on this review are challenging because of several limitations in the literature. Improvements in future research include the use of consistent definitions of gestational weight gain and outcomes of interest, assessment of confounders, and better collection of weight and weight gain data.

Outcomes of maternal weight gain.

OBJECTIVES: The RTI International-University of North Carolina at Chapel Hill Evidence-based Practice Center (RTI-UNC EPC) systematically reviewed evidence on outcomes of gestational weight gain and their confounders and effect modifiers, outcomes of weight gain within or outside the 1990 Institute of Medicine (IOM) guidelines, risks and benefits of weight gain recommendations, and anthropometric measures of weight gain. DATA SOURCES: We searched MEDLINE Cochrane Collaboration resources, Cumulative Index to Nursing & Allied Health Literature, and Embase. REVIEW METHODS: We included studies published in English from 1990 through October 2007. We excluded studies with low sample size (based on study design: case series <100 subjects and cohorts <40 subjects). RESULTS: Overall, strong evidence supported an association between gestational weight gains and the following outcomes: preterm birth, total birthweight, low birthweight (<2,500 g), macrosomia, large-for-gestational-age (LGA) infants, and small-for-gestational-age (SGA) infants; moderate evidence supported an association for cesarean delivery and intermediate-term weight retention (3 months to 3 years postpartum). The studies reviewed provided strong evidence for the independent association of pregravid weight status and outcomes, moderate evidence for age and parity, and weak evidence for race. Regarding outcomes of weight gain within or outside 1990 IOM guidelines, moderate to strong evidence suggests an association between weight gain below IOM recommendations and preterm birth, low birthweight, SGA birthweights, and failure to initiate breastfeeding, and strong evidence for the association between weight gain above IOM recommendations and high birthweight, macrosomia, and LGA birthweights. Moderate evidence supports an association between weight gain above IOM guidelines and cesarean delivery and postpartum weight retention in the short, intermediate, and long term. Included research is inadequate for objective assessments of the range of harms and benefits of providing all women, irrespective of age, race or ethnicity, or pregravid body mass index (BMI), with the same recommendation for weight gain in pregnancy. CONCLUSIONS: Gestational weight gain is associated with some infant and maternal outcomes. One weight gain recommendation for all women is not supported by the evidence identified in this review. To understand fully the impact of gestational weight gain on short- and long-term outcomes for women and their offspring will require that researchers use consistent definitions of weight gain during pregnancy, better address confounders in their analyses, improve study designs and statistical models, and conduct studies with longer followup.