Impact of in utero exposure to SARS-CoV-2 on children’s hospital admission: a national birth cohort study in England

Abstract

Abstract To examine the impact of in utero exposure to SARS-CoV-2 virus on children’s emergency and planned hospital admissions up to 40 months of age. Nationwide, birth cohort study using multiple linked administrative datasets in England. Children with conception start dates between 1st February and 31st July 2020 and born alive to mothers residing in England, followed for 40 months. In utero SARS-CoV-2 exposure (i.e., maternal infection in pregnancy) during wild-type or Alpha variant dominant periods, characterised via linkage to national testing and hospital data. First emergency or planned admission before 40 months of age of the 262,086 children included, 14,717 (5.6%) were exposed to SARS-CoV-2 in utero: 6,888 (2.6%) during the wild-type period and 7,829 (3.0%) during the Alpha period. Overall, 89,189 children (34.0%) had at least one emergency admission and 24,635 (9.4%) had at least one planned admission. After adjusting for socio-demographic characteristics and maternal chronic conditions, we found no evidence of a difference in time to the first emergency admission among children exposed in utero during the wild-type period compared with children unexposed during either period. Children exposed in the Alpha period had a lower hazard of first emergency admission (adjusted HR: 0.92, 99% CI: 0.87 to 0.97). However, this finding likely reflects changes in testing practice and selection bias, as the association attenuated to null when comparisons were restricted to children whose mothers tested negative during the same variant period. No evidence of a difference was found in the time to the first planned admission between in utero exposed groups and the unexposed group, nor in the time to either the first emergency or planned admission based on the trimester of in utero exposure. In this large national birth cohort in England, we found no evidence of increased hazard of hospital admission by 40 months of age associated with in utero exposure to SARS-CoV-2, in the absence of maternal vaccination. Further follow-up is needed to assess late-onset outcomes and the effect of later circulating SARS-CoV-2 variants. Continued investment in linked maternal-child health data is essential to monitor both immediate and long-term effect of emerging infections during pregnancy.