Declining incidence of low birth weight — impact on perinatal mortality and incidence of cerebral palsy

Abstract

The present study was undertaken to separate the impacts of a declining incidence of low birth weight from the effects of an improved perinatal care on perinatal mortality and incidence of cerebral palsy (CP) in an unselected population of infants and children. In the total population of infants with birth weight 500 g or more born in a Norweigian country (Vestfold) 1970- 84 (n = 34,756) the incidence of low birth weight (500 - 2499 g) declined significantly, from 5% during the 10-year period 1970-79, to 4.1% during the 5-year period 1980 - 84 (p < 0.01). The decline was stronger for very low birth weight infants (500-/1499 g) than for moderately low birth weight infants (1500-2499 g) (31% vs. 13%; p < 0.01). Perinatal mortality decresed form 17 to 10.3.permill. (p < 0.01), and the incidence of CP from 2.6 to 2.1 .permill. (p = 0.4). Because low birth weight infants were at increased risk for perinatal death and CP, the declining incidence of low birth weight was attributable 41.4% of the decline in perinatal mortality, and 40% of the reduction of CP form the period 1970-79 to 1980 - 84. Strategies for prevention of low birth weight may be important for further reduction of perinatal mortality and handicaps related to low birth weight.