Changing prognosis for very low birth weight infants.

Obstetric decisions regarding extremely premature infants are based in part on their long-term prognosis. This review pools data from perinatal center reports to update mortality and morbidity trends for each subgroup of very low birth weight infants. Throughout the last 10 years, there has been steady and statistically significant improvement in neonatal mortality rates among inborn very low weight infants (1500 g or less). The most substantial improvement of the 1980s over the late 1970s is in the 750-1000-g birth weight group, in which today's infants have about a 70% chance of surviving if they have access to neonatal intensive care. Mortality in infants born weighing less than 750 g is still very high; overall about two-thirds die, but results are highly variable across centers, with several centers reporting 50-70% survival. The rate of serious long-term disability increases with decreasing birth weight, but within each birth weight group, the proportion of survivors who have serious handicaps has not changed significantly since the introduction of neonatal intensive care. For infants born between 1975-1985, 26% of surviving infants with birth weights below 800 g, 17% of survivors with birth weights between 750-1000 g, and 11% of survivors with birth weights between 1000-1500 g have major handicaps at 1 or 2 years of age. Because many very sick newborns who previously would have died are now surviving, an increasing rate of handicap might have been expected.