Data extraction and management
Two researchers (HWL, ELT) independently screened titles and abstracts,
and subsequently reviewed the full text of each selected study to assess
for eligibility. Any discrepancies in initial screening between the two
researchers were resolved by discussion with a third author (MB). The
following data were extracted from the selected studies: participant
demographics (sample size, age, geographic), study design, interventions
(spontaneous vaginal delivery (SVD), operative VD, planned/ elective CS
or unplanned/ emergency CS), primary and secondary outcomes, outcome
measures and definitions (if given). If the primary outcome was not
stated explicitly, the main outcome reported in the conclusion or the
outcome included in the study’s power calculation was recorded. The
authors of the studies were not contacted to clarify the details of
primary outcome. The composite outcomes were recorded in the extraction
of outcomes.