Background: Australian bariatric surgery (BSurg) rates more than doubled between 2005 and 2015, with around half being women of childbearing age. Few studies have reported gestational weight gain (GWG), and maternal and neonatal outcomes in pregnant women after sleeve gastrectomy. Aims: This retrospective cohort study compared GWG, maternal and neonatal outcomes of women with and without a history of BSurg from one urban Australian hospital. Materials and Methods: Eligible participants were pregnant women with and without a history of BSurg who gave birth between 2016 and 2020. A woman with BSurg was matched to one woman without BSurg based on age, pre-pregnancy body mass index (BMI) and estimated date of confinement. Demographic, pregnancy and GWG outcomes were sourced from hospital data and medical records. Chi-squared and t-tests were used to compare data between groups. Results: There were 210 participants (105 in each group) with a median pre-pregnancy BMI of 30.5 kg/m². The main BSurg type was sleeve gastrectomy (n = 87). Neonates of women post-BSurg had lower birthweights (BSurg: 3175 ± 484 g; non-BSurg: 3419 ± 562 g; p < 0.001). GWG (BSurg: 9 [4.9–13.9]kg; non-BSurg: 8.9 [3–15.3]kg, p = 0.987) and adherence to the Institute of Medicine's GWG recommendations (BSurg: 24%; non-BSurg: 22%, p = 0.897) were similar between groups. Women who conceived < 12 months after BSurg had on average 4.8 kg lower GWG (p < 0.001) and more had insufficient GWG (BSurg < 12 months:61%; BSurg ≥ 12 months: 25%, p = 0.002). Conclusion: Neonates of women who had BSurg prior to pregnancy had lower birthweights than neonates of women of similar age, pre-pregnancy BMI and confinement date. Delaying pregnancy for 12 months post-BSurg may be associated with adequate GWG.