From Bariatric Surgery to Conception: The Ideal Timing to Optimize Fetal Weight

Abstract

Purpose Bariatric surgery (BS) increases the risk of small for gestational age (SGA) neonates. Guidelines recommend postponing pregnancy for 12–24 months, but optimal surgery-to-conception interval (BSCI) remains uncertain. We aimed to evaluate the impact of BSCI on birth weight and SGA. Materials and Methods Retrospective cohort study of 42 pregnancies following BS, including Roux-en-Y gastric bypass, gastric sleeve, adjustable gastric banding and biliopancreatic diversion. Neonates were classified as SGA if birth weight < 10th percentile. Optimal BSCI was obtained from the analysis of ROC curves, and pregnancies were compared by that cut-off. Results There was a linear association between BSCI and birth weight and an inverse association with SGA, with each additional month of BSCI translating into additional 4.5 g (95%CI: 2.0–7.0) on birth weight and -6% risk of SGA (95%CI: 0.90–0.99). We established a cut-off of 24.5 months of BSCI for lower risk of SGA. Pregnancies conceived in the first 24 months had a more than tenfold increased risk of SGA (OR 12.6, 95%CI: 2.4–66.0), even when adjusted for maternal age, gestational diabetes and inadequate gestational weight gain. Conclusion BSCI was associated with birth weight and SGA. Our results are in line with the recommendations of BSCI of at least 24 months to reduce the risk of SGA.