Contribution to the definition of high-risk groups of low birth weight infants

Follow-up studies of low birth weight infants concern usually infants selected on the basis of either the birthweight--inferior or equal to 1500 g--or the gestational age: the upper limit is 31 or 32 weeks. To determine the most pertinent criterium, mortality and neurodevelopmental outcome at two years were compared in 3 groups, selected on the above criteria from a cohort of 369 infants with a birthweight below 2,000 grams admitted in 1983 in the neonatal unit of the University hospital of Lille. Under 1501 grams the rate of small for gestational age infants is high: it could be a part of the explanation for the high rate of minor sequelae. When cohorts are selected on the basis of gestational age, it appears that mortality is low at 32 weeks but the rate of major and moderate sequelae is still high: that fact must be considered when premature induced delivery comes in discussion. Because these criteria select different high risk populations, mortality and neurodevelopmental follow-up studies should include all infants with gestational age inferior or equal to 32 weeks and/or birthweight inferior or equal to 1,500 grams.