Changes in birth certificate-reported prevalence of congenital anomalies at live birth during the COVID-19 pandemic: a nationwide study of 26 million United States live births.

Background: Although the majority of studies have indicated that maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination are not associated with neonatal birth defects, it is relevant to examine whether the disease burden changed during the COVID-19 pandemic, as other influencing factors may have also changed. We aimed to compare the birth certificate-reported prevalence of congenital anomalies at live birth before and during the pandemic. Methods: Using public birth data, all live births from 2016 to 2022 in the United States of America (USA) were retrospectively included. The birth certificate-reported prevalence at live birth of selected congenital anomalies identified from the birth certificate, including anencephaly, meningomyelocele/spina bifida, cyanotic congenital heart disease (CCHD), congenital diaphragmatic hernia, omphalocele, gastroschisis, limb reduction defect, cleft lip, cleft palate, Down syndrome, chromosomal disorder, and hypospadias, was estimated and compared by calendar year of birth using logistic regression. Results: A total of 26,345,765 live-born infants from 2016 to 2022 were included. The mean gestational age of the infants was 38.4 weeks (SD = 2.1 weeks), 48.9% were female babies, and 96.7% were singleton. The overall reported prevalence of congenital anomalies was highest in 2018 (3.51‰, 95%CI = 3.45‰-3.57‰) and has since shown a decreasing trend [3.38‰ (95%CI = 3.32‰-3.44‰) in 2019 and 3.35‰ (95%CI = 3.29‰-3.41‰) in 2022]. Using 2019 as a reference, it did not differ in 2020 and 2021 [odds ratio (OR) = 1.01 (0.98-1.03) and OR = 1.00 (0.98-1.03), respectively, after adjusting for maternal age, ethnicity/race, and socioeconomic status] and was slightly lower in 2022 [OR = 0.97 (0.95-0.99)]. For the majority of the congenital anomalies, the reported prevalence during the pandemic (2020-2022) remained unchanged or showed a decreasing trend (i.e., gastroschisis and Down syndrome) compared with that in 2019. The reported prevalence of CCHD was higher in 2021 and 2022 than in 2019. However, the increase had begun before the pandemic, and after correction for multiple comparisons, only the 2021 contrast remained significant. Segmented regression confirmed a significant pre-pandemic upward trend in CCHD with a level change dated to infants born in March 2020. When exposure was re-indexed by estimated year of conception, neither pandemic conception cohort differed from the 2019 conception cohort [2020: OR = 1.03 (0.97-1.09); 2021: OR = 1.02 (0.97-1.08)]. The direction of these results was consistent when stratified by gestational age (≥37 or <37 weeks), with wider intervals in the preterm stratum. Conclusions: The birth certificate-reported prevalence of congenital anomalies at live birth did not increase during the COVID-19 pandemic in the USA and decreased for several specific anomalies. The higher reported prevalence of CCHD continues a trend that began before the pandemic and is null once exposure is aligned with organogenesis.