A comparison of relevant statistics from National Maternity Hospital, Dublin, Ireland and University Hospital, Newark, New Jersey, USA, for the years 1983-1989, revealed that after removal of major confounding factors, such as a fourfold difference in < 2500 gram births and an about tenfold discrepancy in the frequency of lethal congenital defects, the perinatal survival rates in all weight categories were significantly higher in the American center. The findings suggest that optimum perinatal results could not be achieved in an American high risk center with the approximately 6% abdominal delivery rate favored in Dublin. The same data also suggest, however, that the 17.5% rate of abdominal deliveries in Newark was unnecessarily high. The favorable impact of the relatively liberal use of cesarean section might have been derived in this study from a marked reduction of in utero losses, in the absence of an identifiable effect upon the rate of neonatal mortality.