Van der Ham 2012b.

Methods	Multi‐centre, parallel, open‐label RCT Duration of study: December 2009‐January 2011
Participants	Setting: 8 academic and 52 non‐academic hospitals in the Netherlands Participants: 195 women 100 women randomised to early birth (included 100 babies) 95 women randomised to expectant management (included 98 babies) Inclusion criteria Singleton or twin pregnancy with PPROM between 34 and 36 + 6 weeks' gestation who were not in labour within 24 h of PPROM PPROM had to be diagnosed after 26 + 0 weeks Exclusion criteria Monochorionic multiple pregnancy Abnormal (non‐reassuring) cardiotocogram Meconium‐stained amniotic fluid Signs of intrauterine infection Major fetal anomalies HELLP syndrome Severe pre‐eclampsia
Interventions	Intervention: induction of labour with 24 h after randomisation. Induction performed according to national guidelines. After vaginal examination, labour induced with either prostaglandin or oxytocin, or caesarean section performed as soon as feasible in case of planned caesarean. Control: expectant management Monitored according to local protocol until spontaneous birth which could be outpatient or inpatient Daily maternal temperature, monitoring and twice‐weekly blood sampling for maternal leukocyte count and C‐reactive protein measurement Criteria for birth in the expectant group of women Induced at 37 weeks according to national guidelines If planned caesarean section, caesarean section performed as soon as labour commenced Induction of labour < 37 weeks if clinical signs of infection or other fetal or maternal indication for birth Tocolysis and prophylactic antibiotics used according to local protocols Corticosteroids given in PPROM < 34 weeks' gestation Vaginal examinations not performed in the absence of labour
Outcomes	Maternal Antepartum haemorrhage Uterine rupture Umbilical cord prolapse Signs of chorioamnionitis (defined as fever before or during labour and a temperature < 37.5°C on 2 occasions more than 1 h apart before or during labour, or a temperature > 38.0°C on 1 occasion with uterine tenderness) Leukocytosis Maternal or fetal tachycardia (or a foul‐smelling vaginal discharge in absence of any other cause of hyperpyrexia) Maternal sepsis (defined as a temperature > 38.5°C and a positive blood culture or circulatory instability requiring intensive care monitoring) Thromboembolic complications Urinary tract infection treated with antibiotics Endometritis (defined as a temperature > 38.0°C on 2 occasions at least 1 h apart after the 1st 24 h postpartum with associated uterine tenderness) Pneumonia Anaphylactic shock HELLP syndrome Maternal death Other complications Total length of hospital stay Admission to the ICU Mode of birth Need for anaesthesia Fetal Neonatal sepsis: positive blood culture at birth (excluding Staph epidermidis); 2 or more symptoms of infection (apneas, temperature instability, lethargy, feeding intolerance, respiratory distress, haemodynamic instability) within 72 h after birth plus 1 of the following: positive blood culture, C‐reactive protein > 20 mmol/L, positive surface cultures of a known virulent pathogen RDS Wet lung Meconium aspiration syndrome Pneumothorax/pneumomediastinum Asphyxia Late onset neonatal sepsis Hypoglycaemia Necrotizing enterocolitis Hyperbilirubinaemia Intraventricular haemorrhage Periventricular leucomalacia Convulsions Other neurological abnormalities Other complications Intrapartum death Total length of hospital stay and admission Length of stay on NICU
Notes	Rupture of membranes was diagnosed based on history and clinical findings such as gross vaginal fluid loss in combination with other available diagnostic test methods. Gestational age was based either on first trimester ultrasound scan or, in women with a regular cycle, on the first day of the last menstrual cycle if the expected date of birth differed less than 7 days from the estimated by ultrasound. in women with unknown EDD, gestational age was estimated by 2nd trimester ultrasound measurements.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A computer‐generated randomisation schedule was used in a 1:1 ratio using a block size of 4, stratified for centre and parity.
Allocation concealment (selection bias)	Low risk	Randomisation allocation was performed on a central password‐protected web‐based application.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding not possible due to intervention. However this was likely low risk of bias due to objective and specific assessment criteria for outcomes, where lack of blinding did not affect treatment decisions or other aspects of care.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Criteria for sepsis were entered in the database and the case was judged by an independent panel of paediatricians who were unaware of the allocation of randomisation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data analysed on intention‐to‐treat basis. No participants were excluded.
Selective reporting (reporting bias)	Low risk	All a‐priori outcomes were reported on.
Other bias	Low risk	None noted

2 perinatal deaths resulting from lethal congenital abnormalities were excluded from analyses post‐randomisation.

BPD: biparietal diameter of the fetal head
 CSF: cerebrospinal fluid
 EDD: estimated due date
 GBS: Group B Streptococcus/Streptococcal
 HELLP: haemolysis, elevated liver enzymes, and low platelets
 L/S: Lecithin‐sphingomyelin
 NICU: neonatal intensive care unit
 PPROM: preterm prelabour rupture of the membranes
 RCT: randomised controlled trial
 RDS: respiratory distress syndrome
 WBC: white blood cells
 WCC: white cell count