A critical review of the relationship between gestational weight gain and preterm delivery

OBJECTIVE: To review the relationship between gestational weight gain and preterm delivery. DATA SOURCES: We identified published studies through Medline searches (for the period 1980-1996), and we reviewed bibliographies from published articles. METHODS OF STUDY SELECTION: We excluded non-English-language articles and articles that used total weight gain, unadjusted for gestational age. Thirteen articles were identified for review. TABULATION, INTEGRATION AND RESULTS: Eleven of the 13 studies reported a significant association between maternal weight gain and risk of preterm delivery, and most reported that inadequate rate of maternal weight gain was associated with an increased risk (approximately 50-100%) of preterm delivery. Studies examining pattern of gain noted that a low rate of gain during the latter part of pregnancy (but not early pregnancy) was associated with an increased risk of preterm delivery (also approximately 50-100%). The studies' findings were relatively consistent, despite the use of diverse samples, study designs, and analytic strategies. CONCLUSION: The evidence suggests that a lower rate of weight gain during pregnancy is associated with an increased risk of preterm delivery, and that a slow rate of gain during the latter part of pregnancy may be particularly important. To improve our understanding of the mechanisms of these relationships, future studies should examine pattern of gain; they should stratify analyses on the different subtypes of preterm delivery and provide more detailed descriptions of methods for assessing gestational duration.