Objective: To determine whether the lockdown period of the initial COVID-19 surge in New York affected gestational weight gain (GWG), newborn birth weight (BW), and the frequency of gestational diabetes (GDM). Maternal and newborn outcomes during the first wave of the pandemic were compared to those during the same timeframe in the previous two years. Study Design: Retrospective cross-sectional study of all live singleton term deliveries from April 1st to July 31st between 2018-2020 at seven hospitals within a large academic health system in New York. Patients were excluded for missing data on: BW, GWG, pre-pregnancy body mass index (BMI), and gestational age at delivery. We compared GWG, GDM, and BW during the pandemic period (April-July 2020) with the same months in 2018 and 2019 (pre-pandemic) to account for seasonality. Linear regression was used to model the continuous outcomes of GWG and BW. Logistic regression was used to model the binary outcome of GDM. Results: A total of 20,548 patients were included in the study: 6,672 delivered during the pandemic period and 13,876 delivered during the pre-pandemic period. On regression analysis, after adjustment for study epoch and patient characteristics, the pandemic period was associated with lower GWG (β -0.46, 95% CI -0.87 to -0.05), more GDM (aOR 1.24, 95% CI 1.10 to 1.39), and no change in newborn BW (β 0.03, 95% CI -11.7 to 11.8) compared with the referent period. The largest increases in GDM between the two study epochs were noted in patients who identified as Hispanic (8.6% vs. 6.0%; P<0.005) and multiracial/other (11.8% vs. 7.0%; P<0.001). Conclusion: The lockdown period of the pandemic was associated with a decrease in GWG and increase in GDM. Not all groups were affected equally. Hispanic and multiracial patients experienced a larger percentage change in gestational diabetes compared to non-Hispanic white patients.