Perinatal factors and preterm delivery in an Irish obstetric population.

The aim of this study was to ascertain the incidence of preterm delivery, the associated etiological factors and consequent perinatal mortality in an Irish obstetrical population. All deliveries between 24 + 0 and 36 + 6 weeks of gestation that occurred during the five year period 1992-1996 were included in the study. The overall group of preterm deliveries was also analyzed separately as an early preterm group (24 + 0-31 + 6 weeks gestation) and a late preterm group (32 + 0-36 + 6 weeks gestation). The overall incidence of preterm delivery was 5.5% (n = 683) with 1% (n = 122) occurring in the early preterm group and 4.5% (n = 561) in the late preterm group. The etiological factors contributing to preterm delivery in our population together with their frequency of occurrence in both early and late preterm groups are outlined. Spontaneous unexplained preterm delivery, multiple pregnancy, and hypertensive disorders of pregnancy were the commonest etiological factors for preterm delivery. The perinatal mortality rate (PMR) was 57 per 1000 (n = 39) in the preterm group overall with a 213/1000 PMR in the early preterm group and a 23/1000 PMR in the late preterm group.