Outcome measures
The outcome measures were maternal and infant outcomes, mode of
delivery, and gestational age at delivery of the new pregnancies.
Maternal outcomes were recorded as uncomplicated, repeat complete
rupture, partial rupture, peripartum hysterectomy, and abnormally
invasive placenta. Infant outcomes were recorded as healthy, moderate
asphyxia, severe asphyxia, admission to neonatal intensive care unit
(NICU), and perinatal death (stillbirth and neonatal death). All were
categorized into Yes or No.
Mode of delivery was grouped into elective CS, emergency prelabour CS,
and vaginal delivery. Gestational age at delivery was grouped into
weeks: <28, 28-32, 33-36, 37-38, and 39 weeks.
Peripartum hysterectomy was defined as surgical removal of the uterus at
the time of delivery or up to 42 days postpartum, excluding hysterectomy
because of cancer. Abnormally invasive placenta included all types of
morbidly adherent placenta defined by histology, including accreta,
increta, and percreta.
Stillbirth was defined as infant death before birth caused by asphyxia
related to uterine rupture, and neonatal death was defined as death
≤7 days after birth. We defined severe
asphyxia8using diagnostic ICD-10 code P21.0 (asphyxia with 1-minute Apgar score
0–3). We defined moderate
asphyxia8using ICD-10 code P21.1 (asphyxia with 1-minute Apgar score 4–7). NICU
admission was defined as admission due to prematurity. Healthy was
defined as an infant without any complications and no admission to the
NICU.
Characteristics of previous ruptures :
Characteristics of previous ruptures included place of rupture (within
lower uterine segment [LS; reference] and outside LS), gestational
age at rupture (< 37 weeks and ≥37 weeks [reference]),
time of occurrence of rupture (before labour start and after labour
start [reference]), detection time (during CS or postpartum after
vaginal delivery/CS), and presence of perinatal death. In addition, the
inter-delivery interval was included and defined as the time from
complete rupture to new delivery (1 year, 2-3 years [reference], and
≥ 4 years).