Diabetes mellitus, maternal adiposity, and insulin-dependent gestational diabetes are associated with Covid-19 in pregnancy: The INTERCOVID Study

Background: Among non-pregnant individuals, diabetes mellitus (DM) and high body mass index (BMI) increase the risk of Covid-19 and its severity.Objective: To determine whether DM and high BMI are risk factors for Covid-19 in pregnancy and whether gestational diabetes mellitus (GDM) is also associated with covid-19 diagnosis.Study design: INTERCOVID was a multinational study, conducted between March 2020 and February 2021 in 43 institutions from 18 countries, enrolling 2184 pregnant women ≥18 years; 2071 were included in these analyses. For each woman diagnosed with Covid-19, two non-diagnosed women delivering or initiating antenatal care at the same institution were also enrolled. Main exposures were pre-existing DM or high BMI (overweight/obesity defined as ≥25 kg/m2), and GDM in pregnancy. Main outcome was a confirmed diagnosis of Covid-19 based on an RT-PCR test, antigen test, antibody test, radiological pulmonary findings, or ≥2 predefined Covid-19 symptoms at any time during pregnancy or delivery. Relationships of exposures and Covid-19 diagnosis were assessed using generalized linear models with a Poisson distribution and log link function, with robust standard errors to account for model misspecification. We also conducted sensitivity analyses: 1) restricted to those with an RT-PCR or antigen test in the last week of pregnancy; 2) restricted to those with an RT-PCR or antigen test during the entire pregnancy; 3) generating values for missing data using multiple imputation; and 4) analyses controlling for month of enrollment. In addition, among those who were diagnosed with Covid-19, we examined whether having GDM, DM, or high BMI, increased risk for having symptomatic vs. asymptomatic Covid-19.Results: Covid-19 was associated with preexisting DM (RR=1.94, 95% CI=1.55, 2.42), overweight/obesity (RR=1.20; 95% CI=1.06, 1.37), and GDM (RR=1.21; 95% CI=0.99, 1.46). The GDM association was specifically among women requiring insulin, whether they were of normal-weight (RR=1.79, 95% CI=1.06, 3.01) or overweight/obese (RR=1.77, 95% CI=1.28, 2.45). A somewhat stronger association with Covid-19 diagnosis was observed among women with pre-existing DM, whether they were of normal weight (RR=1.93, 95% CI=1.18, 3.17) or overweight/obese (RR=2.32, 95% CI=1.82, 2.97). When the sample was restricted to those with a RT-PCR or antigen test in the week before delivery or during the entire pregnancy, including missing variables using imputation, or controlling for month of enrollment, the observed associations were comparable.Conclusion: DM and overweight/obesity are risk factors for Covid-19 diagnosis in pregnancy, and insulin-dependent GDM is also associated with the disease. It is therefore essential that those women with these co-morbidities are vaccinated