Table 1 Characteristics of Included Studies

Beckmann, 2019 [10] (Australia)

≥37 + 0 weeks’ gestation, Bishop score < 7, residing < 60 min from the hospital

Priming with balloon catheter (n = 215)

Priming with prostaglandin 2 mg gel or 10 mg controlled-release tape (n = 233)

Composite measure of neonatal outcomes comprising of one or more of: admission to a neonatal special or intensive care nursery, need for intubation, and/or external cardiac compressions at birth, neonatal academia at birth, hypoxic ischaemic encephalopathy, neonatal seizure, neonatal infection, persistent pulmonary hypertension of the newborn, stillbirth or neonatal death

Kuper, 2018 [11] (USA)

Parous women ≥39 weeks’ gestation, cervical dilation ≤3 cm, or if 2-3 cm dilated less than 80% effacement, reassuring fetal heart rate monitoring

Priming with balloon catheter, with oxytocin initiated upon readmission (n = 65)

Priming with balloon catheter and concomitant oxytocin infusion (n = 64)

Duration of time from labour ward admission until delivery

Policiano, 2016 [12] (Portugal)

≥41 weeks’ gestation or with a medical indication for labour induction), Bishop score < 6

Priming with balloon catheter (n = 65)

Priming with balloon catheter (n = 65)

Change of Bishop score between application and removal of balloon catheter

Wilkinson 2015, [18] COPRA Trial (Australia)

37–42 weeks’ gestation, Bishop score < 7

Priming with balloon catheter (n = 33)

Priming with balloon catheter (n = 15)

Oxytocin use

Henry 2013 [13] & Austin 2015 [14], FOG Trial (Australia)

Women ≥18 years old, ≥37 weeks’ gestation, Bishop score < 7 and cervical dilation < 2 cm, no regular uterine contractions.

Priming with balloon catheter (n = 50)

Priming with vaginal prostaglandin E2 gel [2 mg for nulliparous and 1 mg for parous women] (n = 51)

Vaginal birth within 12 h of admission, inpatient hours between randomization and birth

Wilkinson 2014 [15], Turnbull 2013 [16] & Adelson 2013 [17], OPRA Trial (Australia)

Women ≥18 years of age, 37–42 weeks’ gestation, living within 40 min of hospital with transport and having a telephone.

Priming with prostaglandin E2 gel [2 mg for nulliparous and 1 mg for parous women] (n = 411)

Priming with prostaglandin E2 gel [2 mg for nulliparous and 1 mg for parous women] (n = 416)

Oxytocin use

Rijnders 2011 [21] (Netherlands)

Women ≥18 years of age, 41 + 5–42 weeks’ gestation, no neonatal infections in previous pregnancies, and negative GBS status.

Amniotomy (at home) followed by 12 h of expectant management (n = 270)

Referral to an obstetrician for monitoring and induction of labour according to local guidelines. (n = 251)

Spontaneous birth without intervention.

Biem 2002 [20](Canada)

≥ 37 weeks’ gestation, a reactive non-stress test, Bishop score ≤ 6, and reliable means of transportation to the hospital.

Priming with prostaglandin E2 10mg insert, and admitted 24 h after insertion (n = 150)

Priming with prostaglandin E2 10mg insert (n = 150)

Proportion in labour or delivered by 24 h, and maternal satisfaction.

Sciscione 2001 [19] (USA)

≥ 37 weeks’ gestation, Bishop score ≤ 5, access to a telephone, and living within 30 min from the hospital with reliable means of transportation.

Priming with balloon catheter followed by oxytocin infusion the next morning of cervical ripening until extrusion of catheter (n = 61)

Priming with balloon catheter, then oxytocin infusion was started once the catheter was extruded (n = 50)

Change in Bishop score from the initial assessment until reassessment the following morning for outpatients, or when the Foley was extruded for inpatients.