Early-life exposures in infants born during and after the COVID-19 pandemic: A comparative prospective observational study of the CORAL and FLORAL birth cohorts.

BACKGROUND: The CORAL 2020 birth cohort examined health outcomes and feeding practises in infants born during the COVID-19 pandemic, a period of reduced social mixing and altered healthcare utilization during a critical period of immune development. The 2025 FLORAL (FoLlow-on from CORAL) cohort was established to determine whether findings from the CORAL cohort were specific to the pandemic period or reflected broader evolving trends. METHODS: FLORAL is a prospective observational birth cohort study recruiting term infants born between March and May 2025 across three Dublin maternity hospitals using almost identical methodology to the CORAL cohort. Assessments included parent-completed questionnaires and in-patient study visits. Outcomes at 6 months were compared between FLORAL and CORAL cohorts to examine differences in early-life exposures. RESULTS: Of 574 infants whose parents provided consent, 485 completed the enrolment questionnaire. At 6 months, 442 participants completed the six-month follow-up questionnaire and 440 attended the in-person study visit. Demographic characteristics were broadly comparable between cohorts. FLORAL infants had numerically higher rates of reported infections (33.3% vs. 28%, p = .12), hospitalization (13.1% vs. 5.1%, p < .001), and antibiotic exposure (13.1% vs. 6.2%, p = .002) compared with CORAL infants. However, the introduction of allergenic foods occurred significantly more frequently in FLORAL, with peanut introduced in 44% of infants compared with 13.6% in CORAL (p < .0001). CONCLUSION: Compared with pandemic-born infants, post-pandemic infants experienced increased infection-related healthcare utilization and increased antibiotic exposure, alongside sustained high breastfeeding rates and substantially earlier allergen introduction. These may influence microbiome development and later atopic outcomes.