Data Management
YY, IH and YZ independently extracted information from the included
studies using a predefined data coding sheet. Authors were contacted to
obtain more information if related data was ambiguous or not included in
the publications. In cohorts reporting different diet quality scores,
the results based on the largest sample size were included in the
meta-analysis to avoid sample overrepresentation. When diet quality
measures were provided on equal sample sizes, results for the diet
quality score with the most items were included. In cohorts where diet
quality was reported at different time points in pregnancy, second
trimester measures were selected. For each of these decisions,
sensitivity analyses were then performed using other reported results
from the same cohort to test the robustness of the findings. For each
study, results from the model adjusting for the most confounding
variables were selected.
YY and IH independently assessed the quality and risk of bias of each
included study with the Newcastle–Ottawa Scale
(NOS)29. The sum of points was used to categorize
overall study quality as either high (7-9), moderate (4–6) or low
(0-3).