Study selection, Characteristics, and Quality
The study selection process is shown in Figure 1. We identified 6113
unique publications from the databases and one from other sources. After
title and abstract assessment, 98 publications were selected for
full-text screening. A total of 34 articles met our eligibility and were
included in this review, and 33 were included in meta-analyses.
As shown in Table S2, only two studies33,34 were of
moderate quality (NOS = 6) and all other studies were of high quality
(NOS 7-9). The detailed characteristics of included studies are
presented in Table S3. The sample sizes and study periods of the cohorts
ranged from 41 to 72,072, and 1991 to 2017 respectively. All studies but
one were conducted in pregnant women from the general population, with
variable exclusion criteria related to maternal prepregnancy BMI,
history of preterm birth, and maternal comorbidities. One study was
conducted in pregnant women with obesity or history of
GDM35. Four cohorts were conducted in
Singapore36, Malaysia33,
Mexico37, and a French Caribbean
island38. The other cohorts were conducted in
high-income countries located in Europe, North America, and Oceania. Six
studies used at least one self-reported outcome, while all other studies
used valid assessments including medical records or standardized
measurements. For dietary assessment, four33,37,39,40studies used dietary recalls, one36 used both dietary
recalls and food diaries, three35,41,42 used
non-validated FFQ, and the remainder of studies used a validated FFQ.
Studies varied as to the timepoint and period of dietary assessment.
Four studies43-46 assessed diet in prepregnancy and
other studies assessed diet during pregnancy. Diet quality was assessed
using 22 different scores, with versions of aHEI, HEI and MD scores most
frequently assessed (Table S4). There was large variability of potential
confounders included in the multivariable models across studies (Table
S5).