Etiology and perinatal medical significance of prematurity below 1,500 g

305 preterm babies with birthweight below 1500 g were delivered at our centre between 1991 and 1994. Classification according to etiology shows that more than half (52.7%) of these deliveries had to be induced secondary to underlying fetal or maternal pathology. A more efficient tocolysis could have prevented up to one third of these deliveries (31.4%). The main cause of each preterm delivery was defined according to Whitfield's etiological classification. In decreasing order of frequency we found hypertensive disorders of pregnancy, multiple pregnancy, preterm premature rupture of membranes, preterm labour and vaginal bleeding in the third trimester. The majority of these deliveries (88.6%) were prenatal referrals, reflecting widespread regionalization of obstetric services in Switzerland. Nevertheless, 64 women (24.2%) with threatening preterm labour before the 32nd week of gestation had to be denied admission to our hospital because of shortage of neonatal intensive care beds, or had to be transferred from our hospital to another offering perinatal facilities during the study period (1991-1994). Acute lack of neonatal intensive care unit beds in Switzerland requires closer attention in the future.