ObjectivesWe herein evaluated the effects of gestational weight gain (GWG) on postpartum pelvic floor function using transperineal ultrasound (TPUS).MethodsWe analyzed retrospectively the data from 228 primiparous women with singleton pregnancies who were evaluated for postpartum pelvic floor function between February 2022 and October 2022. According to the 2009 Institute of Medicine guidelines regarding GWG, subjects were separated into three groups: inadequate GWG, recommended GWG, and excessive GWG. All underwent TPUS 6–10 weeks postpartum to assess bladder neck descent between rest and Valsalva (BND), retrovesical angle at Valsalva (RVA), urethral rotation angle between rest and Valsalva (URA), the area of levator hiatus at Valsalva (LHA), and abnormal pelvic floor function. Univariate and multivariate regression analyses were applied to explore the association measures between GWG and the pelvic floor. A P‐value <.05 was considered statistically significant.ResultsOf the 228 primiparous women, 113 (49.6%) showed excessive GWG. Univariate analysis revealed that there were no statistical differences in ultrasonic parameters of the pelvic floor among the three groups (P > .05). After adjusting for potential confounders and using the recommended GWG group as a reference group, inadequate GWG was significantly associated with BND ≥25 mm (OR = 0.36, 95% CI = 0.14–0.93), and excessive GWG was significantly associated with uterine prolapse (OR = 2.79, 95% CI = 1.13–6.92).ConclusionsGWG was associated with the ultrasonic parameters of the female pelvic floor in the early postpartum period.