Effects of low-glycemic-index diets in pregnancy on maternal and newborn outcomes in pregnant women: a meta-analysis of randomized controlled trials.

PURPOSE: Maternal diet with a high glycemic index (GI) is associated with fetal overgrowth and higher infant body adiposity. Effects of low-GI diet on maternal and newborn outcomes have been assessed in both healthy pregnancy and gestational diabetes mellitus, but the results remain inconclusive. This meta-analysis aimed to examine the effects of low-GI diets on maternal and newborn outcomes.

METHODS: PubMed, Clinical Trials, and Cochrane Library databases were searched for relevant randomized trials up to January 2016. Random- or fixed-effects models were used to calculate combined treatment effects.

RESULTS: A total of 11 trials involving 1985 women were eligible for analysis. This meta-analysis assessed 7 maternal and 11 newborn outcomes. Of these, gestational weight gain (GWG), fasting blood glucose (FBG), newborn birth weight, ponderal index (PI), proportion of macrosomia, and large for gestational age (LGA) were investigated in more than 8 trials. Compared with control diets, low-GI diets significantly reduced FBG (weight mean differences (WMD) = -0.18 mmol/L, 95 % CI: -0.33, -0.02), 2-h postprandial glucose level (WMD = -0.33 mmol/L, 95 % CI: -0.54, -0.12), and the proportion of LGA (RR = 0.52, 95 % CI: 0.31, 0.89). A lower GWG (WMD = -0.69 kg, 95 % CI: -1.74, 0.36) and birth weight (WMD = -0.10 kg, 95 % CI: -0.23, 0.03) were also observed without significant differences. Heterogeneity was observed in the GWG, FBG, and birth weight analyses. Low-GI diets did not affect other maternal and newborn outcomes. In subgroup and sensitivity analyses, the intervention effects of low GI on GWG and FBG varied.

CONCLUSIONS: Low-GI diets may have beneficial effects on maternal outcomes for those at risk of developing high glucose levels, without causing adverse effects on newborn outcomes. However, results should be interpreted with caution because of the evidence of heterogeneity and limited number of studies.