A Cochrane review included 5 studies with a total of 153 subjects. There was no significant difference in either of the primary outcomes; macrosomia (birthweight greater than 4000 g) (RR 3.20, 95% CI 0.14 to 72.62; 2 trials, n=61) and operative birth, caesarean birth being the only outcome reported (RR 1.09, 95% CI 0.66 to 1.77; 3 trials, n=71). No significant differences were found in any other outcomes measured, which may reflect the small number of trials suitable for meta-analysis and the small number of participants in the included studies. No significant differences were found in perinatal mortality (RR 2.33, 95% CI, 0.38 to 14.32; 3 trials, n=71), fetal anomaly (RR 1.07, 95% CI 0.07 to 15.54; 2 trials n=61), maternal hypoglycaemia (RR 3.00, 95% CI 0.35 to 25.87; 2 trials, n=61) or maternal hyperglycaemia (RR 7.00, 95% CI 0.39 to 125.4; 2 trials, n=61), or small-for-gestational age (average RR 1.40, 95% CI 0.10 to 18.71; 2 trials, n=61) .
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) and by imprecise results (few patients and wide confidence intervals).