Characteristics of the study population.

Objective
To evaluate the association between gestational weight gain (GWG) and adverse neonatal outcomes in women who conceived using assisted reproductive technology (ART).
Methods
The National Vital Statistics System (NVSS) 2019–2021 provided data for this retrospective cohort study. Adverse neonatal outcomes included premature birth, small for gestational age (SGA), large for gestational age (LGA), macrosomia, low birth weight (LBW), and other abnormal conditions. Any adverse outcome was defined as at least one of the above six outcomes. Multivariate logistic regression analysis was employed to evaluate the associations between GWG and different outcomes, after adjusting for confounding factors. These associations were further assessed in subgroups of maternal age at delivery, paternal age at delivery, preconception body mass index (BMI), gestational age, maternal race, parity, gestational diabetes, and gestational hypertension.
Results
Totally 108201 women were included, with 22282 in the insufficient GWG group, 38034 in the sufficient GWG group, and 47885 in the excessive GWG group. Women with insufficient GWG [odds ratios (OR) = 1.11, 95%CI: 1.07–1.16, P<0.001] and excessive GWG (OR = 1.14, 95%CI: 1.10–1.18, P<0.001) had significantly greater risks of any adverse outcome than those with sufficient GWG. In contrast to sufficient GWG, insufficient GWG was associated with significantly elevated risks of premature birth (OR = 1.42, 95%CI: 1.35–1.48, P<0.001), SGA (OR = 1.45, 95%CI: 1.37–1.53, P<0.001), LBW (OR = 1.47, 95%CI: 1.37–1.58, P<0.001), and other abnormal conditions (OR = 1.32, 95%CI: 1.27–1.39, P<0.001), and excessive GWG was associated with significantly lower risks of premature birth (OR = 0.86, 95%CI: 0.83–0.90, P<0.001), SGA (OR = 0.79, 95%CI: 0.75–0.83, P<0.001), LBW (OR = 0.85, 95%CI: 0.79–0.91, P<0.001), and other abnormal conditions (OR = 0.92, 95%CI: 0.88–0.96, P<0.001). Infants born to women with insufficient GWG had significantly decreased risks of LGA (OR = 0.71, 95%CI: 0.66–0.75, P<0.001) and macrosomia (OR = 0.68, 95%CI: 0.63–0.74, P<0.001), and infants born to women with excessive GWG had significantly increased risks of LGA (OR = 1.50, 95%CI: 1.44–1.56, P<0.001) and macrosomia (OR = 1.60, 95%CI: 1.51–1.69, P<0.001).
Conclusion
Insufficient GWG and excessive GWG were associated with increased risks of any adverse outcome than sufficient GWG in women who conceived with ART, indicating the applicability of recommended GWG by the Institute of Medicine (IOM) in this population.