Neonatal and "perinatal" mortality rates by birth weight.

Neonatal and "perinatal" mortality rates by birth weight were compared for Sheffield and for England and Wales. The fall in neonatal mortality rate for Sheffield infants weighing 2500 g or less was partly due to the excessive fall in numbers in the 1000 g or less group: this effect was also present in England and Wales but was less pronounced. Perinatal mortality rates may be lowered either by reducing (a) the number of stillbirths, (b) the number of preterm live births, or (c) by salvaging a greater percentage of the latter. For liveborn births it is suggested that the second approach would be better than the third. So far there is no evidence that superintensive care for those weighing 1000 g or less reduces their mortality rate.