Effect sizes were similar between all diabetes in pregnancy groups: insulin (17 studies26–32,41,42,44,46,47,50–52,55,56 n = 2872) (Fig. 6c), glyburide (5 studies33–35,48,49, n = 684) (Fig. 6d) and placebo (OR 0.68, 95% CI 0.47–1.00; I2 = N/A, p = 0.05) (1 study36, n = 470). Here, INS is linked to diabetes mellitus.