Process of study selection, data extraction and risk of bias
assessment
The online tool Rayyan QCRI was used for registration of the selection
process.10 Duplicate articles were automatically
excluded. Two assessors independently screened all titles and abstracts.
Eligible articles were retained for full-text reading. Uncertainties at
each stage were discussed and resolved by consensus with a low threshold
for inclusion.
One reviewer extracted all data on pregnancy course and complications
occurring during delivery and the postpartum period, which was
thereafter verified by the second reviewer. Uncertainties at each stage
were again discussed and resolved by consensus. All data were described
in a narrative format.