Impact of Bariatric Surgery on Pregnancy: A Systematic Review and Meta-analysis

Introduction: Bariatric surgery (BS) is an increasingly common intervention for women of reproductive age with morbid obesity, however the optimal timing of pregnancy following surgery has not yet been fully established, particularly as it impacts both obstetric and neonatal outcomes. Methods: Systematic search of Medline, EMBASE, EMCARE, and Cochrane databases identified 2468 studies for screening; 129 met inclusion criteria. The meta-analysis included women who underwent various BS procedures followed by pregnancy. Outcomes were analyzed using a random-effects model, comparing early (<12 months) and later (>12 months) post-surgery conception. Maternal outcomes included gestational weight gain (GWG), gestational diabetes (GDM), pre-eclampsia, preterm birth, caesarean delivery, induction of labour, postpartum hemorrhage (PPH), anaemia, and internal hernia. Neonatal outcomes included Apgar scores, birthweight, gestational age, Neonatal intensive care unit (NICU) admissions, macrosomia, intrauterine growth restriction (IUGR), and perinatal death. Results: Bariatric surgery reduced pre-pregnancy BMI by 14 kg/m² (95% CI: 13– 15kg/m ² , I² = 93.1%, p=0.000). Postoperative pregnancies had lower odds of gestational diabetes (OR 0.67, 95% CI: 0.53–0.85), pre-eclampsia (OR 0.60, 95% CI: 0.45–0.79), and macrosomia (OR 0.35, 95% CI: 0.24–0.50), but higher odds of intrauterine growth restriction (OR 2.09, 95% CI: 1.92–2.27), prematurity (OR 1.24, 95% CI: 1.04-1.47) and NICU admission (OR 1.39, 95% CI: 1.17–1.65). Mean GWG in women who conceived within 12 months of BS was 5.2kg (95% CI: 2.0, 8.0), compared to 10.2 (95% CI: 9.5, 11,1) in women who conceived >12 months after BS. PPH and caesarean rates were similar between post-BS pregnancies and obese controls. The prevalence rate of anaemia was 26% (95% CI: 22–31) and Vitamin D deficiency was 69.0% (95% CI: 61.8, 76.2). Conclusion: Bariatric surgery reduces obstetric risks of GDM, hypertensive disorders, and macrosomia. However, conception within 12 months is associated with lower GWG. BS increased odds of IUGR and preterm birth without significant difference in peri-natal mortality. Nutritional deficiencies, including anaemia, and fat-soluble vitamins, require close monitoring, particularly in early post-surgical pregnancies.