Data vary widely: disability rates pegged for very premature babies.(Obstetrics)

NEW YORK -- About one in four extremely premature infants who survive will have at least one major developmental disability. Dr. John M. Lorenz said at an obstetrics symposium sponsored by Columbia University and New York Presbyterian Hospital.

The estimate comes from an analysis of available data, which vary widely and should be interpreted with caution. However, they do point to certain trends. Mortality decreases dramatically with each week from 22 to 25 completed weeks' gestation. The proportion of live births that survive without major disability increases with each week from 23 to 26 weeks' gestation, while there appears to be little change in the proportion of survivors with major disability from 24 to 26 weeks, said Dr. Lorenz, professor of clinical pediatrics at Columbia University and Children's Hospital of New York.

Data on survival are generally easier to interpret than are those on neurodevelopmental outcome. However, even survival studies vary widely with regard to the age at which survival is reported (most report survival only to discharge from the neonatal intensive care unit), the amount of information provided about other factors potentially affecting survival (such as prenatal steroid exposure), and the institution's policies regarding use of obstetric interventions and/or intensive care in extremely early gestations.

Data from 18 studies published between 1990 and 2003 of infants born within tertiary care centers in North America suggest that mean survival of those born at 22 weeks' gestation is 13%, with a range of 0%-21%. At 23 weeks, the mean is 28%, with a range of 0%-46%. The mean at 24 weeks is 51%, with a range of 17%-68%. At 25 weeks, the mean is 71% (50%-82%) and at 26 weeks, 81% (74%-93%).

"Every week you can delay delivery makes a big difference in survival, but be aware of ...