Antepartum bed rest is widely prescribed after preterm premature rupture of the membranes (PPROM), although its effectiveness to prevent preterm birth has not been demonstrated. This pilot randomized controled trial (RCT) aims to access the impact of bed rest in maternal and neonatal outcomes in pregnancies complicated by premature rupture of the membranes.

Aims - To access the impact of bed rest in latency time to delivery, chorioamnionitis incidence and other maternal and neonatal outcomes in pregnancies complicated by PPROM, thus enabling proper sample size calculation for future powered RCT.

Study population and Sample size - Eligible patients included those with single pregnancies with PPROM at 24+0-33+6 weeks of gestation who were admitted to and delivering at our tertiary center. PPROM was diagnosed on the basis of patient's history and sterile speculum examination with visualization of amniotic fluid pooling in the vagina and/or leaking from the cervical canal. Exclusion criteria included indication for immediate delivery on admission (chorioamnionitis, placenta abruption, cord prolapse, signs of fetal hypoxia/distress), fetal malformations, multiple gestation, and maternal immunosuppressive disease. Considering future sample size calculation based upon assumed differences between groups regarding latency and infection, we aimed a sample of 30 participants.

Randomization - A pilot unblinded randomized controlled trial (RCT) in a 1:1 allocation ratio between two groups (complete bed rest versus activity restriction after PPROM). Simple random allocation sequence was generated by the investigators and implemented by sequentially numbered sealed envelopes. Participants were enrolled by physicians after hospital admission and written informed consent was obtained before randomization. The trial was conducted in a single tertiary center of the Portuguese national health system after approval by its ethical committee.

Statistical analysis - An intention-to-treat analysis was performed with a significance level of 5%.

Inclusion Criteria:

• single pregnancies AND
• PPROM at 24+0-33+6 weeks of gestation AND
• admitted to our tertiary center.

Exclusion Criteria:

• indication for immediate delivery on admission (chorioamnionitis, placenta abruption, cord prolapse, signs of fetal hypoxia/distress)
• fetal malformations
• multiple gestation
• maternal immunosuppressive disease

Patient eligibility is based on gender identity because we will include only pregnant women