The incidence and outcomes of perinatal asphyxia in spontaneous extreme preterm birth: a retrospective cohort study.

OBJECTIVES

To determine the incidence and outcome of perinatal asphyxia (PA) in spontaneous extreme preterm birth (PTB) between 24 and 28 weeks gestation.

METHODS

We conducted a retrospective cohort study (2010-2019) at a Dutch tertiary center, including singleton spontaneous PTBs with active neonatal management. PA was defined as a 5-min Apgar score ≤5, umbilical artery pH≤7.00, base deficit >12 mmol/L, and need for ongoing resuscitation. Cases were classified as proven PA (all criteria met), suspected PA (Apgar≤5 only if blood gas data missing), or no PA. Neurodevelopment was assessed at 2 years corrected age. Multiple imputation addressed missing data. Logistic regression, adjusted for gestational age (GA), was used to evaluate associations with infant mortality, cerebral injury, and neurodevelopmental impairment (NDI).

RESULTS

Among 138 neonates, 84 % had no PA, 12.3 % suspected PA, and 3.6 % proven PA. After imputation, the estimated incidence of PA was 5.0 %. PA was not significantly associated with infant mortality (aOR 1.07; 95 % CI 0.13-8.87; p=0.95) or intraventricular hemorrhage (aOR 1.62; 95 % CI 0.26-10.39; p=0.61). NDI occurred in two infants with PA.

CONCLUSIONS

PA occurred more frequently in this extreme preterm cohort than in term neonates, yet did not independently influence mortality or morbidity. A major limitation is the use of ACOG criteria, originally developed for term births, which may have led to over- or underestimation of PA's true incidence and impact. Although based on few confirmed cases, findings suggest PA, may not be a major independent predictor of adverse outcome in extreme PTB.