Trends in Extreme Neonatal Hyperbilirubinaemia: A Longitudinal Population-Based Case-Control Study

To determine the incidence, causes, and clinical associations of cases of extreme neonatal hyperbilirubinaemia in South Australia.

This was a population-based case-control study of neonates ≥ 36 weeks gestation with extreme hyperbilirubinaemia (plasma bilirubin level ≥ 450 μmol/L) in South Australia over a 12-year period, between January 2010 and December 2021. Cases of extreme hyperbilirubinaemia were detected via a state-wide pathology system. Further details were obtained using medical records. Population data from the SA Health Pregnancy Outcome Unit was used as the control group.

A total of 68 cases were identified. The overall incidence of extreme hyperbilirubinaemia for the 12-year period was 28.6/100 000 births, higher than a previously published Australian estimate of 9.4/100 000 live births reported over a similar period and determined by clinician reporting. Extreme hyperbilirubinaemia was associated with Asian ethnicity, ventouse delivery and early discharge. A large peak in 2020 was temporally associated with the onset of the SARS-CoV-2 pandemic.

The incidence of extreme hyperbilirubinaemia stayed mostly stable over 12 years in South Australia and was higher than previously described via voluntary clinician reporting. Population-based surveillance monitoring via laboratory systems is likely to be more reliable than voluntary clinician reporting. A spike in incidence in 2020 may have occurred due to pandemic-related changes in maternity and neonatal care practices.