The very preterm infant - a population-based study

Objectives. The aim of this study was to assess perinatal risk factors and the survival of the very preterm infant in comparison with birth beyond 32n d birthweek, as well as health care utilization by mothers and infants in t he Northern Health Region of Sweden. Design. A population-based study was designed of all children (66,646) born in the Northern Health Region of Sweden during 1991-1996 and registered in the Swedish Medical Birth Registry. Methods. Maternal and perinatal factors of infants born very preterm, that is, at less than or equal to 27 and 28-31 weeks of gestation, were analyzed for relative risk (RR), and a 95% confidence interval (CI), and compared w ith those of infants born 32-36 weeks of gestation. Results. Of the 66,646 infants registered, 3,493 (5.2%) were born at 32-36 weeks, 394 (0.6%) at 28-31 weeks, and 199 (0.3%) at 22-27 weeks' gestation. No special socio-demographic maternal factors characterized these preterm births. The very preterm infants were more prone to perinatal complications such as premature rupture of the membranes (PROM) (RR=4.13; 95% CI=3.07-5. 55), and both FROM and hemorrhage (RR=7.80; 95% CI=3.43-17.72). Infants bor n very preterm were more often twins, growth-retarded, malformed, and affec ted by sepsis and respiratory distress. There was significantly better surv ival of preterm infants born at less than or equal to 27 weeks' gestation i f their mothers were given tertiary perinatal care. For infants born extrem ely preterm, survival tended to be better if they were delivered by cesarea n section. Conclusion. The very preterm birth is more often than not a result of a com plicated pregnancy. The infant is often sick before birth, and for its surv ival is highly dependent on the highest level of perinatal care.