The COVID-19 pandemic and prevalence of gestational diabetes: Does gestational weight gain matter?

Previous European reports indicated an increased prevalence of gestational diabetes mellitus (GDM) among relatively lean cohorts during the COVID-19 pandemic.^, Less is known about how the pandemic affected the prevalence of GDM in the United States, specifically among those with morbid obesity. Pregnant people with obesity have been reported to be at increased risk of excessive gestational weight gain (GWG) during the COVID-19 pandemic, which may have further increased the risk of GDM among this group. The primary aim of our study was to investigate whether the prevalence of GDM increased among our delivering patients, with consideration of their weight status, during the COVID-19 pandemic. The secondary aim of our study was to determine whether GDM diagnosis was associated with increased GWG.

This retrospective cohort study included patients with a singleton, term birth who delivered before the COVID-19 pandemic (January 2019 to May 2020) and during the COVID-19 pandemic (July 2020 to November 2021) at a single academic institution. As recommended by the American College of Obstetricians and Gynecologists, prenatal patients at our institution are screened for GDM between 24 and 28 weeks of gestation. Patients that were screened before March 2020 (the declared start of the COVID-19 pandemic) would have been delivered, at term, by the end of May 2020. Therefore, the pre–COVID-19 period was defined as January 2019 to May 2020 to capture term deliveries where GDM screening occurred before March 2020. We included a 1-month “washout” period (June 2020) to ensure only those diagnosed with GDM during the COVID-19 period were captured (July 2020 to November 2021). This study was approved by the University of Tennessee Graduate School of Medicine Institutional Review Board (IRB#4907).

Patients with a preexisting type 1 or 2 diabetes mellitus, a multigestation pregnancy, a preterm delivery, or an unknown gestational age at delivery were excluded. Data collected on delivery admission included height, prepregnancy weight, weight at delivery, maternal age, race and ethnicity, and diagnosis of GDM. Prepregnancy body mass index (BMI) was calculated using height and prepregnancy weight. To examine potential differences in patients with higher classes of obesity, standard weight status categories based on BMI were created. These included underweight (BMI of <18.5 kg/m²), healthy (BMI of 18.5 to <25.0 kg/m²), overweight (BMI of 25.0 to <30.0 kg/m²), obese class 1 (BMI of 30.0 to <35.0 kg/m²), obese class 2 (BMI of 35.0 to <40.0 kg/m²), and obese class 3 (BMI of ≥40.0 kg/m²). GWG was calculated by prepregnancy weight deducted from weight at delivery. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology reporting guidelines. Binary and multiple regression analyses were used to identify potential differences in GDM diagnosis before the COVID-19 pandemic vs during the COVID-19 pandemic, controlling for potentially confounding factors (including weight status, maternal and gestational age, GWG, and race and ethnicity). Student t tests were used to assess the effect of the COVID-19 pandemic on GWG, stratified by weight status, among those with GDM. A P value of .05 was considered statistically significant. Data were analyzed using the SPSS (version 28; IBM Corporation, Armonk, NY).

During the COVID-19 pandemic, 12.2% of patients were diagnosed with GDM, compared with 9.9% of patients before the COVID-19 pandemic (P<.001). Those with GDM diagnosis had an associated lower GWG relative to those without GDM, in the unadjusted and adjusted models (P<.001) (Table). Among those diagnosed with GDM, there was no significant difference in GWG in the pre–COVID-19 or during–COVID-19 groups or when stratified by any weight status categories (data not shown) (P>.05).

The prevalence of GDM increased by 22.2% among delivering patients during the COVID-19 pandemic. However, no significant increase in GWG, even among those with obesity, was noted. Similar to other cohorts, GWG was significantly lower among those with GDM, potentially reflecting standard clinical care regimens of dietary therapy for this population. A potential mechanism for this increased GDM trend, despite no significant change in GWG, remains unexplored, but maternal stress is a proposed contributor to gestational hyperglycemia. Future research is needed to determine whether this increase was correlative or if causal events related to the pandemic lead to increased gestational hyperglycemia and whether GDM diagnosis will return to pre–COVID-19 values.