Clinical Characteristics and Incidence of Spontaneous Preterm Birth in Symptomatic COVID-19 Pregnant Women: An Observational Study

Abstract

Background: There is limited data regarding COVID-19 and preterm birth. Most published studies do not exclude induced preterm deliveries or women at higher risk for preterm birth. Objective (s): To determine the incidence of spontaneous preterm delivery in pregnancies complicated by maternal COVID-19 infection with no other independent risk factors for preterm birth. Study design: This was an observational study of symptomatic women diagnosed with COVID-19 during the third trimester of pregnancy who delivered at Flushing Hospital Medical Center in Queens, New York between March 1 and May 1, 2020. IRB approval was obtained. Charts of symptomatic women who were confirmed COVID-19 positive by RT-PCR in the third trimester were reviewed. Patient information collected included gestational age at diagnosis of COVID-19, obstetrical history, comorbidities, x-ray findings, and blood work. Women with a history of preterm birth, short cervix in current pregnancy, and multiple gestations were excluded. Statistical evaluation for normally distributed continuous variables was done using a student’s t-test, and for dichotomous variables, a Chi-square analysis or Fisher’s exact test was used. A multiple regression analysis model was used to correlate the relationship of clinical variables to the gestational age at delivery. Results: 24 pregnant women met initial criteria, 17 of which delivered in the time period stated. Preterm delivery rate in our sample size was 29% (n=5). Our institution’s preterm delivery rate for a similar time-period in 2019, using the same exclusion and inclusion criteria, was 2.7%. When comparing COVID-19 positive women that delivered preterm to COVID-19 positive women who delivered at term, the gestational age on admission was lower in the preterm cohort (weeks 34.1 ± 1.5 weeks versus 38.0 ± 1.7; p<0.001). Multiple regression analysis showed the following variables correlated with the gestational age at birth: gestational age on admission (Coefficient 0.95, (95% CI 0.86 - 1.03; p<0.001), white blood count (Coefficient 0.142, 95% CI 0.07 - 0.22; p=0.002), and lymphocyte percentage (Coefficient 0.038, 95% CI 0.01 - 0.06; p=0.008). Conclusion (s): Symptomatic COVID-19 infection seems to be a significant risk factor for spontaneous preterm delivery, especially if the gestational age on admission is below 37 weeks, the white blood cell count is low, or the lymphocyte percentage is decreased.