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.

Contents

• Preface
• Executive Summary
• 1. Introduction
  • Background
  • Key Questions and Analytic Framework
  • Analytic Framework for Outcomes of Maternal Weight Gain
  • Production of This Evidence Report
  • Uses of This Report
• 2. Methods
  • Literature Review Methods
  • Literature Synthesis
  • External Peer Review
• 3. Results
  • KQ 1: Outcomes of Gestational Weight Gain
  • KQ 3: Outcomes of Weight Gain Within or Outside IOM Recommendations
  • KQ 5: Anthropometrics of Weight Measurement
• 4. Discussion
  • Outcomes of Maternal Weight Gain (KQ 1 and KQ 3)
  • KQ 2: Confounders and Effect Modifiers of Outcomes of Maternal Weight Gain
  • KQ 4: Risks and Benefits of Gestational Weight Gain Recommendations
  • KQ 5: Anthropometrics of Weight Measurement During Pregnancy
  • Limitations
  • Future Research Directions
• Appendixes
  • Appendix A. Search Strategy
  • Appendix B. Sample Data Collection Forms
  • Appendix C. Evidence Tables
  • Appendix D. List of Excluded Studies
  • Appendix E. Acknowledgments
• References

Prepared for: Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services.¹ Contract No. 290-02-0016. Prepared by: RTI International-University of North Carolina Evidence-based Practice Center, Research Triangle Park, North Carolina.

Suggested citation:

Viswanathan M, Siega-Riz AM, Moos M-K, Deierlein A, Mumford S, Knaack J, Thieda P, Lux LJ, Lohr KN. Outcomes of Maternal Weight Gain, Evidence Report/Technology Assessment No. 168. (Prepared by RTI International-University of North Carolina Evidence-based Practice Center under Contract No. 290-02-0016.) AHRQ Publication No. 08-E009. Rockville, MD: Agency for Healthcare Research and Quality. May 2008.

This report is based on research conducted by the RTI-UNC Evidence-based Practice Center (EPC) under contract to the Agency for Healthcare Research and Quality (AHRQ), Rockville, MD (Contract No. 290-02-0016). The findings and conclusions in this document are those of the author(s), who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or of the U.S. Department of Health and Human Services.

The information in this report is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This report is intended as a reference and not as a substitute for clinical judgment.

This report may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.

No investigators have any affiliations or financial involvement (e.g., employment, consultancies, honoraria, stock options, expert testimony, grants or patents received or pending, or royalties) that conflict with material presented in this report.

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