Neonatal encephalopathy mortality rate in Aotearoa, New Zealand: review of national data 2010-2020.

BACKGROUND

Neonatal encephalopathy (NE) is a condition that affects newborn and can lead to long-term neurological impairments and death. Hypoxic ischaemic encephalopathy is the subset of NE with evidence of a hypoxic ischaemic insult. In Aotearoa New Zealand, national data have been collected for infants ≥37 weeks since 2010 and ≥35 weeks from 2016. Although the mortality rate associated with NE has not been a focus of annual reports, it is an important outcome for counselling whānau (families) and for international comparison.

METHODS

The Perinatal and Maternal Mortality Review Committee (PMMRC) dataset was used to calculate mortality rate for cases of moderate/severe NE for two gestational groups, 35 weeks to 36 weeks+6 days (2016-20) and ≥37 weeks (2010-2020). Annual mortality rates in infants ≥37 weeks with NE for the period 2010-20 were calculated overall and by prioritised ethnic group.

RESULTS

In the PMMRC dataset, there was frequently a history of fetal distress or antenatal sentinel event with the vast majority of included infants having low Apgar scores and requiring resuscitation at birth. The mortality rate was 0.23/1000 births (95% CL 0.17-0.29) for infants ≥37 weeks with no significant change over the study period. The mortality rate for infants with NE between 35 and 36+6 weeks was 0.68/1000 births (95% CL 0.31-1.28), giving a relative risk of 2.99 in preterm compared with term infants with NE. No statistical difference in mortality by prioritised ethnic group was demonstrated.

CONCLUSIONS

There has been no improvement in mortality rates for infants with NE despite ongoing efforts to improve early recognition and treatment. Preterm infants were at significantly higher risk of death. The analysis did not demonstrate any ethnic differences in mortality associated with NE.