Background: With 42% of adult Americans obese and 2/3rd of Americans overweight or obese, increased body mass index (BMI) is fast becoming normalized. There is a need to continue highlighting the association between pre-pregnancy obesity and adverse pregnancy outcomes in the country. The aim of the present study is to determine the association between increasing pre-pregnancy BMI and pregnancy outcomes.Methods: We utilized the United States Vital Statistics records to collate data on all childbirths in the United States between 2015 and 2019. We determined the association between increasing pre-pregnancy BMI and adverse pregnancy outcomes using multivariate analysis. Neonatal outcomes measures include the 5-min Apgar score, neonatal unit admission, neonates receiving assisted ventilation > 6 hours, neonatal antibiotics use, and neonatal seizures. Maternal outcomes include cesarean section rate, mothers requiring blood transfusion, unplanned hysterectomy, and intensive care unit admission. In addition, we controlled for maternal parameters such as race/ethnicity, age, insurance type, and preexisting conditions such as chronic hypertension, and prediabetes. Other covariates include paternal race, age and education level, gestational diabetes mellitus (GDM), induction of labor, weight gain during pregnancy, gestational age at delivery, and delivery weight. Results: We studied 15 627 572 deliveries in the US vital statistics records between 2015 and 2019. Among these women, 3.36% were underweight, 43.19% were with a normal BMI, 26.34% were overweight, 14.73% were in the obese class I, 7.23% were in the obese class II, and 5.14% in the obese class III. Increasing pre-pregnancy BMI was associated with significant adverse outcomes across all measures of maternal and neonatal outcomes. Conclusion: Increasing pre-pregnancy body mass index is associated with significant adverse pregnancy outcomes. Since pre-pregnancy BMI is a modifiable risk, women should be encouraged to lose weight before pregnancy to improve pregnancy outcomes.