D'Anna 2015.

Study characteristics
Methods	Study type: parallel RCT
Participants	220 obese pregnant women from Italy Inclusion criteria: pre‐pregnancy BMI ≥ 30 kg/m2, singleton gestation Women were 12 to 13 weeks' gestation at study entry. Exclusion criteria: previous gestational diabetes, pre‐gestational diabetes, first trimester glycosuria (urine glucose value 10 mg/dL or greater), first trimester fasting plasma glucose 126 mg/dL or greater, or random plasma glucose 200 mg/dL or greater, concomitant treatment with corticosteroids, hypertension or renal or hepatic disease. Location: obstetric departments of 2 university hospitals located in Messina and Modena, Italy Timeframe: January 2011 to April 2014
Interventions	Intervention: 4 g myo‐inositol plus 400 mg folic acid daily (2 g myo‐inositol + 200 mg folic acid orally twice a day), and nutritional and lifestyle counselling (N = 110) Duration of myo‐inositol supplementation: from trial entry until the end of pregnancy Comparison: 400 mg folic acid daily (200 mg folic acid orally twice a day), and nutritional and lifestyle counselling (N = 110)
Outcomes	Maternal: occurrence of gestational diabetes, changes of insulin resistance from the first trimester to the performance of the OGTT performed at 24‐28 weeks as measured by the homeostasis model assessment of insulin resistance, caesarean section, gestational hypertensive disorders Criteria used to diagnose gestational diabetes: IADPSG Infant: preterm delivery, shoulder dystocia, macrosomia (birthweight > 4000 g), neonatal hypoglycaemia, neonatal transfer to intensive care unit
Notes	Sample size calculation: conducted Intention‐to‐treat analysis: yes Funding source: grant from Messina University Conflict of interest: none reported ClinicalTrials.gov trial registration NCT01047982 Further information was received following email contact with the authors
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Computer‐generated random number list prepared by an investigator with no clinical involvement with the trial."
Allocation concealment (selection bias)	Low risk	"Allocation concealment was ensured by central randomisation." "After the research investigator had obtained the patients consent, he telephoned a contact who was independent of the recruitment process for allocation assignment."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Trial was open label so blinding of participants and clinicians was not possible.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Data collectors were blinded to treatment allocation and the data came from the patients record." "objective measurements of primary laboratory outcomes."
Incomplete outcome data (attrition bias) All outcomes	Low risk	9% loss to follow‐up overall. More participants chose to drop out of the myo‐inositol group (n = 8) than the 'placebo' group (n = 0).
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes are reported on.
Other bias	Low risk	Appears free of other bias. The authors do not report any potential conflicts of interest.