Gestational Diabetes Risk and Low Birth Weight After Metabolic Bariatric Surgery: a Complex Interplay to be Balanced

Metabolic bariatric surgery (MBS) is known to improve the obstetric outcomes of women with obesity and to prevent gestational diabetes (GD). To what extent does MBS decreases GD, without incurring at additional risks is a matter of concern.

A retrospective case-control study to compare the pregnancy outcomes of women previously submitted to MBS to those of age and preconception body mass index (PC BMI) matched non-operated controls.

Pregnancies of women after MBS (n = 79) and matched controls (n = 79) were included. GD was significantly less frequent after MBS (7.6% vs. 19%; p = 0.03). Fasting blood glucose (76.90 ± 0.77 vs 80.37 ± 1.15 mg/dl, p < 0.05; 70.08 ± 1.34 vs. 76.35 ± 0.95 mg/dl; p < 0.05, first and second trimesters respectively) and birth weight (2953.67 ± 489.51 g vs. 3229.11 ± 476.21 g; p < 0.01) were significantly lower after MBS when compared to controls. The occurrence of small-for-gestational-age (SGA) was more frequent after MBS (22.8% vs. 6.3%; p < 0.01), but no longer significant after controlling for smoking habits (15.5% vs. 6%, p = 0.14). There were no significant differences in gestational weight gain, prematurity rate nor mode of delivery between groups.

MBS was associated with a lower prevalence of GD than observed in non-operated women with the same age and BMI. After controlling for smoking, this occurred at the expense of a lower birth weight. Our data reinforces the hypothesis that MBS has body weight independent effects on glucose kinetics during pregnancy with distinctive impacts for mother and offspring, which need to be balanced.