Effect sizes were similar across all diabetes in pregnancy groups: insulin (8 studies26,28,31,32,41,43,45,46, n = 1716) (Fig. 3c), glyburide (OR 1.16, 95% CI 0.42–3.17, I2 = N/A, p = 0.34) (1 study49, n = 159) or placebo (OR 0.87, 95% CI 0.40–1.86; I2 = N/A, p = 0.71) (1 study36, n = 482). Here, INS is linked to diabetes mellitus.