[Epidemiology, morbidity and mortality for infants with a gestational age of 24-31 weeks]

To describe the epidemiology, in-hospital morbidity and mortality until discharge from hospital for infants born with gestational age (GA) 24-31 weeks.

All newborns with GA 24-31 weeks, born in 2000-2005 and with antenatal care in the former Vejle County were included. The study comprised two data sources. 1. "Neobase", a database comprising data on the treatment for all newborns admitted to the Neonatal Unit, 2. The Perinatal Audit for Vejle County - where all perinatal deaths are registered.

A total of 275 infants were born with GA 24-31 weeks, of whom 89 were born with GA < 24-27 weeks. The prevalence of births at 24-31 weeks were 9.2 per 1,000 births and 3.0 per 1.000 births with GA < 24-27 weeks. Thirty infants (11%) died before first discharge and for GA 24-27 weeks the mortality was 29%. Forty-six percent of all infant were from a pregnancy with more than one fetus. There was a significant increased risk of intraventricular haemorrhage of grade 2-4 for infants from multiple pregnancies (p < 0,05). Risk of birth before 32 weeks of gestation was 20 times higher for infants from multiple pregnancies. Thirty-nine percent of all infants received treatment with surfactant. A significantly higher proportion of infants delivered by caesarean section received surfactant treatment compared to infants delivered vaginally (p < 0.001), even though median GA was higher (30 and 29 weeks, respectively).

A comparison with The Danish national study in infants with extremely low gestational age and birth weight from 1994-1995, reveals that the prevalence of births at 24-27 gestational weeks is stable or slightly increasing, while mortality has declined significantly. Almost half of all infants born before 32 weeks are from multiple pregnancies. Infants born by caesarean section more frequently received surfactant treatment.