Dietary patterns before and during pregnancy and maternal outcomes: A systematic review

Background: Hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) are common maternal complications during pregnancy, with short- and long-term sequelae for both mothers and children. Objective: Two systematic review questions were used to examine the relation between 1) dietary patterns before and during pregnancy, 2) HDP, and 3) GDM. Methods: A search was conducted from January 1980 to January 2017 in 9 databases including PubMed, Embase, and Cochrane. Two analysts independently screened articles using a priori inclusion and exclusion criteria; data were extracted from included articles, and risk of bias was assessed. After qualitative synthesis, a conclusion statement was drafted for each question and the evidence supporting the conclusion was graded. Results: Of the 9103 studies identified, 8 [representing 4 cohorts and 1 randomized controlled trial (RCT)] were included for HDP and 11 (representing 6 cohorts and 1 RCT) for GDM. Limited evidence in healthy Caucasian women with access to health care suggests dietary patterns before and during pregnancy that are higher in vegetables, fruits, whole grains, nuts, legumes, fish, and vegetable oils and lower in meat and refined grains are associated with reduced risk of HDP, including preeclampsia and gestational hypertension. Limited but consistent evidence suggests certain dietary patterns before pregnancy are associated with reduced risk of GDM. These protective dietary patterns are higher in vegetables, fruits, whole grains, nuts, legumes, and fish and lower in red and processed meats. Most of the research was conducted in healthy, Caucasian women with access to health care. Insufficient evidence exists on the associations between dietary patterns before and during pregnancy and risk of HDP in minority women and those of lower socioeconomic status, and dietary patterns during pregnancy and risk of GDM. Conclusions: Although some conclusions were drawn from these systematic reviews, more research is needed to address gaps and limitations in the evidence.