Cotton 1984.

Methods	A single‐centre unmasked randomised controlled trial.
Participants	47 women with a diagnosis of PPROM between 26 + 0 and 34 + 0 weeks' gestation at Hermann Hospital (Houston, Texas, USA). 25 (22 available for analysis) women were randomised to the intervention group and 22 (22 available for analysis) women were randomised to the control group.
Interventions	Amniocentesis versus no amniocentesis.
Outcomes	Latency period (days from rupture of membranes to birth; reported as a count of women in different latency period categories). Gestation at birth. Birthweight. Apgar scores. Fetal death. Neonatal death. Neonatal sepsis. Fetal sepsis. Respiratory distress syndrome. Transient tachypnoea. Intraventricular haemorrhage. Pneumothorax. Persistent ductus arteriosus. Seizures. Hyperbilirubinaemia. Metabolic problems. Apnea. Feeding difficulties. Days of postnatal hospitalisation (after discharge of mother). Cardiotocographic abnormality in labour (fetal distress). Maternal antepartum hospitalisation. Maternal postpartum hospitalisation. Maternal postpartum endometritis.
Notes	Days of postnatal hospitalisation could not be included in our review because data were presented as the median and range, which was insufficient to calculate the mean difference between the groups.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation	Unclear risk	Not described.
Allocation concealment	Unclear risk	Not described.
Blinding (participants and personnel)	High risk	The nature of the intervention prohibited participant and clinician blinding.
Blinding (outcome assessment)	Unclear risk	Outcome assessor blinding is not described, therefore the risk of bias arising from this is unclear.
Incomplete outcome data addressed All outcomes	Low risk	Loss of participants to follow‐up and exclusion of participants after randomisation are described adequately.
Free of selective reporting	High risk	Several outcomes listed in the methods section are not described in the results section. Some outcomes are reported only as showing no difference between the 2 groups, without any quantitative data.
Free of other bias	Unclear risk	The number of women with multiple gestations is not reported. These women were not excluded from the study, but a subgroup analysis of their effect has not been described. Therefore, the risk of bias arising from the inclusion of women with multiple gestations in the analyses is unclear.