Risk assessment of survival and morbidity of infants born at less than 24 completed weeks of gestation

Background: Infants born at the threshold of viability have a high risk of mortality and morbidity. The British Association of Perinatal Medicine (BAPM) provided updated guidance in 2019 advising a risk-based approach to balancing decisions about active versus redirected care at birth.
Aims: To determine the survival and morbidity of infants born between 22 to 24 completed weeks of gestation. To develop a scoring system to categorise infants according to risk for mortality or severe adverse outcome.
Methods: A retrospective, observational study of infants who received neonatal care in a single centre from 2011 to 2021. Data were collected on mortality, morbidity and two-year neurodevelopmental outcomes. Each infant was risk categorised utilising the proposed tools in the BAPM (2019) framework. A composite adverse score for either dying or surviving with severe impairment was created.
Results: Four infants born at 22 weeks, 49 at 23 weeks and 105 at 24 weeks of gestation were included. The overall mortality rate was 23.4%. Following risk categorisation there were 8 (5.1%) extremely high risk, 44 (27.8%) high risk and 106 (67.1%) moderate risk infants. The rate of dying or surviving with severe impairment for extremely high risk, high risk and moderate risk were 100%, 88.9% and 53% respectively. The proportions with the composite adverse outcome differed significantly according to the risk category (p<0.001).
Conclusions: When applying a scoring system to risk categorise infants, high rates of dying or surviving with severe impairment were found in infants born at 22 or 23 weeks of gestation.