The impact of COVID-19 infection on neonatal birth weight and outcomes

Since its outbreak in 2019, the novel severe acute respiratory syndrome coronavirus-2 (COVID-19) outbreak has had a devastating impact worldwide. Pregnancy has been shown to worsen the clinical outcome in those affected with COVID-19 infection. While data demonstrate poorer maternal outcomes in those infected with COVID-19, published studies on neonatal outcomes after antenatal maternal infection are conflicting-specifically as it relates to neonatal birth weight. We hypothesize that maternal COVID-19 infection increases the risk for small-for-gestational age (SGA) neonatal birth weight.

(1) To estimate the association between antenatal maternal COVID-19 infection and the risk for SGA and (2) to assess whether gestational timing of infection or severity of COVID-19 infection differentially impacts the risk of SGA.

This was a retrospective cohort study that included all pregnant patients with COVID-19 infection and that randomly selected uninfected controls from October 2020 to June 2022 at a single tertiary care center. Multivariable logistic regression was performed to estimate the independent effect of maternal COVID-19 infection on SGA neonatal birth weight. We used similar logistical regression models to estimate the independent effect of COVID-19 exposure on SGA stratified by trimester and COVID-19 severity.

Of 1011 patients in the study, 502 patients had COVID-19 infection. Overall, COVID-19 infection was not associated with an increased risk of SGA, adjusting for confounding by maternal age, hypertension, pre-gravid body mass index (BMI), and race. However, first trimester infection was associated with a twofold increased risk in SGA (adjusted odds ratio [aOR], 2.3; 95% confidence interval [CI], 1.1-5.1), compared to uninfected controls, while infection in the second and third trimesters was not associated with SGA. Moderate/severe disease was associated with a twofold increased risk of SGA (aOR, 2.1; 95% CI, 1.1-3.5) compared to uninfected controls.

While COVID-19 infection was not uniformly associated with SGA in the whole cohort, individuals with moderate/severe disease or those exposed in the first trimester had an increased risk of delivering an SGA neonate. Fetal growth surveillance for COVID-19 infection can be reserved for those with moderate/severe infection or those infected in the first trimester.