Data extraction
Two reviewers (X.L.L and H.Q.L) independently extracted the relevant
data from the eligible articles using standard forms. The data extracted
included information about the first author, the year of publication,
country, study setting, study design, type of participants, age of study
participants, overall sample size, scales used to ascertain traumatic
birth or PTSD, time of traumatic birth/ PTSD ascertainment, and the
number of events (trauma birth and PTSD). Two reviewers resolved
discrepancies through discussion, and any disagreements between the two
reviewers were resolved by the third reviewer (R.H.X).