Metformin for prevention of cesarean delivery and large-for-gestational-age newborns in non-diabetic obese pregnant women: a randomized clinical trial

OBJECTIVE: To evaluate the use of metformin for preventing cesarean deliveries and large-for-gestational-age (LGA) newborn (NB) outcomes in non-diabetic obese pregnant women. SUBJECTS AND METHODS: This is a randomized clinical trial with obese pregnant women, divided into 2 groups: metformin group and control group, with followed-up prenatal routine. The gestational age of participants was less than or equal to 20 weeks and were monitored throughout entire prenatal period. For outcomes of delivery and LGA newborns, absolute risk reduction (ARR) and the number needed to treat (NNT) were calculated with a 95% confidence interval (CI). RESULTS: 357 pregnant women were evaluated. From the metformin group (n = 171), 68 (39.8%) subjects underwent cesarean delivery, and 117 (62.9%) subjects from the control group (n = 186) had intercurrence (p < 0.01). As for the mothers’ general characteristics, there was significance for marital status (p < 0.01). Maternal-fetal results presented reduced preeclampsia (p < 0,01). Primary prophylactic results presented an ARR of 23.1 times (95% CI: 13.0-33.4) with NNT of 4 (95% CI: 3.0-7.7) and no significant values for LGA NB (p > 0.01). Secondary prophylactic outcomes presented decreased odds ratio for preeclampsia (OR = 0.17, 95% CI: 0.10-0.41). CONCLUSION: The use of metformin reduced cesarean section rates, resulted in a small number of patients to be treated, but it did not reduce LGA NB. Administering a lower dosage of metformin from the early stages to the end of treatment may yield significant results with fewer side effects. Arch Endocrinol Metab. 2020;64(3):290-7