Alberico 2017.

Methods	Study design: multicentre open‐labelled randomised controlled trial. Duration of study: 4 years (recruitment phase). Study dates: March 2010 ‐ March 2014 (recruitment phase).
Participants	Setting: 8 'centres' in 3 countries (Italy, Slovenia, Israel). Inclusion criteria: pregnant women, older than 18, with singleton pregnancy, vertex presentation and diagnoses of gestational diabetes in this pregnancy. Exclusion criteria: diagnosis of overt diabetes, prior caesarean section, obstetrical contraindications to vaginal delivery, maternal pregnancy‐related disease or non‐reassuring fetal well‐being necessitating prompt delivery, uncertain gestational age, known fetal anomaly, Bishop score > 7, or estimated fetal weight of 4000 g at enrolment. Participants randomised (#): 425 women (530 women were recruited, 59 women opted out and 46 women were not eligible). Characteristics for planned subgroup analysis: Parity: mixed. Both nulliparous and multiparous women included (% presented in Table 1 of manuscript). 125/214 (59.4%) nulliparous women in planned birth group versus 104/211 (49.3%) nulliparous women in expectant approach group. 87/214 (40.6%) multiparous women in planned group versus 107/211 (50.7%) multiparous women in the expectant approach group.
Interventions	Planned birth: N = 214 women. Between 38‐39 weeks of gestation, women in this group were admitted to the ward and induction of labour was performed. "IOL will be performed using dinoprostone, 2 mg vaginally, or dinoprostone, 0.5 mg intracervically in 6‐8 hours intervals (up to 5 doses) or dinoprostone 10 mg vaginal device. Once the patient’s Bishop score exceeds 7 or regular contractions are diagnosed, patients will be transferred to the delivery ward for artificial rupture of membranes or oxytocin augmentation as indicated. Patients, in which cervical ripening does not occur (Bishops score < 7) after 5 attempts with prostaglandin E2 (PGE2), will be offered either oxytocin or Foley catheter induction or caesarean section, according to protocol" (Published Protocol, Maso et al 2011:4). 2 women in this group (0.9%) presented with spontaneous onset of labour. Expectant approach: N = 211 women. Women enrolled in this group (between 38‐39 weeks' gestation) were followed up twice weekly by electronic fetal heart rate monitoring and biophysical profile until 41 weeks' gestation, when induction of labour was then offered. "...patients enrolled in the conservative management arm will be followed up twice weekly by Electronic Fetal Heart Rate monitoring and Biophysical Profile. Patients will be followed up until 41 weeks' gestation. Women, who do not deliver by this gestational age, will be admitted for IOL. IOL will be offered when non‐reassuring fetal status is suspected. All patients in the conservative arm will undergo fetal weight ultrasound estimation prior to IOL. Patients with estimated fetal weight of over 4000 g will be offered a caesarean section" (Published Protocol, Maso et al 2011:4). 50 women in this group (23.7%) underwent induction of labour for "obstetric or medical indications".
Outcomes	Outcomes considered in the review and reported in or extracted from the study: outcome data for serious maternal morbidity, caesarean section, instrumental birth, intact perineum, postpartum haemorrhage, admission to ICU, perinatal mortality rate, shoulder dystocia, large‐for‐gestational age, birth trauma, respiratory distress syndrome, neonatal hypoglycaemia, neonatal hyperbilirubinaemia, admission to NICU.
Notes	Funding: The Institute for Maternal & Child Health, IRCCS, Burlo Garofolo "offered human and financial resources to carry out the project". Trial authors’ declaration of interest: none declared.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomisation was centralised and coordinated by the Clinical Epidemiology and Biostatistics Unit (IRCCS) using a computer based method. The randomisation list was blocked and stratified by centre."
Allocation concealment (selection bias)	Low risk	"The allocation concealment was guaranteed through the use of consecutively numbered and sealed opaque envelopes."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants: “The study was an open‐label trial because of the practical impossibility to blind either healthcare professionals or patients to the allocation group“. Personnel: “The study was an open‐label trial because of the practical impossibility to blind either healthcare professionals or patients to the allocation group“.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not stated explicitly but unlikely given following extract from study report. “General information on recruited patients, outcomes and randomization group will be indicated in an appropriate paper questionnaire in the first instance and then reported on an electronic database accessible from different study sites in the second instance. In each participating centre, medical personnel will fill up the electronic form directly.“
Incomplete outcome data (attrition bias) Maternal‐perineum intact	High risk	Outcome data available for all women randomised (induction 214, expectant 211) other than perineal trauma where data are available for 198/211, 94% (induction) and 175/214, 82% (expectant).
Incomplete outcome data (attrition bias) Maternal‐all outcomes (other than intact perineum)	Low risk	Outcome data available for all women randomised (induction 214, expectant 211) other than perineal trauma where data are available for 198/211, 94% (induction) and 175/214, 82% (expectant).
Incomplete outcome data (attrition bias) Neonatal‐all outcomes	Low risk	Outcome data available for all infants of mothers randomised with exception of hyperbilirubinaemia, which is available for 93.45% of babies of women in the induction of labour group and 92% in the expectant management group.
Selective reporting (reporting bias)	Low risk	Published and registered protocol available. All outcomes stated in protocol other than 10‐minute Apgar score and uterine rupture reported in paper.
Other bias	Low risk	No other obvious risk of bias identified.

ICU: intensive care unit
 IOL: induction of labour
 NICU: neonatal intensive care unit