Preterm birth subtypes
The primary study outcome was PTB < 37 completed weeks’
gestation. PTB was further categorized as spontaneous PTB or
provider-initiated PTB.1 Births that result from
spontaneous preterm labour and PPROM were classified as spontaneous PTB,
while preterm birth that resulted from labour induction or caesarean
delivery for maternal or fetal indications were classified as
provider-initiated PTB. As a secondary outcome, we assessed the outcome
of early PTB < 34 weeks’ gestation.