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Preconception bariatric surgery increases the risk for small-for-gestational-age (SGA) infants and possibly for preterm birth and low birthweight neonates. However, factors that contribute to these adverse birth outcomes are poorly understood. Objective To synthesize available evidence on the predictors of SGA, preterm birth, and birthweight following bariatric surgery.


A literature search was conducted with two databases (PubMed and PsycINFO) to obtain relevant studies.Results A total number of 61 studies were included in this review.


across studies were largely consistent in excluding surgery-to-conception interval, maternal comorbidities (diabetes, hypertension, anemia), smoking status, and maternal age as predictors of SGA, preterm birth, and birthweight. In contrast, most studies found that restrictive (vs malabsorptive) procedures, higher gestational weight gain, and higher maternal glucose levels were associated with better birth outcomes. Findings were highly mixed for the effect of surgery-to-conception weight loss, pre-pregnancy body mass index, maternal micronutrients, and maternal lipid levels on birth outcomes. The examination of other factors such as maternal gastrointestinal symptoms and alcohol use was limited to one study, therefore no conclusions could be made.


This review identified factors that appear to be associated (e.g., surgery type, glucose levels) or not associated (e.g., surgery-to-conception interval) with birth outcomes following bariatric surgery. The mixed findings (e.g., micronutrients) and the limited number of studies (e.g., alcohol use) on several variables highlight the need for further investigation. Additionally, future studies may benefit from examining interactions among predictors and expanding to assess additional predictors such as maternal mental health.