Decreasing perinatal mortality--increase in cerebral palsy morbidity.

Abstract

Ever-increasing efforts to help high-risk babies to survive at birth and in the neonatal period are important and necessary. There are good prospects-i.e., many healthy survivors-but also the disadvantage-a slowly increasing group of children who have sustained brain injuries, some of them with several serious impairments. These assertions are made in reports concerning the epidemiology of cerebral palsy (CP) published in the recent issues of this journal (1, 2). Is this a true and generally representative pattern? And, if so, how can it occur, despite all medical efforts and new technologies? General achievements: Positive side. The perinatal mortality (PNM) in most developed countries all over the world has been decreasing during recent decades, although the starting-points, the rates of decrease and the present rates of PNM differ from one region to another. The lowest rates are reported from the Nordic countries and from Japan. The decline there has occurred in all the birthweight groups, but it is most striking among very low birthweight infants (Fig. 1). In Sweden in 1973 PNM was 819 per 1 OOO births for birthweights of less than 1 OOO g. In 1983 it was 364 and now it is still lower (Fig. 1). The decrease in PNM has not resulted in any “compensatory” increase in mortality later on during the first year of life (3). The decline in infant mortality in the 1970s and early 1980s in Sweden has been due to the fall in the early neonatal mortality rate, which has mainly affected low birthweight infants (3). The gain in terms of the improved survival rate for non-handicapped infants is a large one, but it is hidden in the health statistics and therefore easily neglected. The gain is greater when there is a high starting-level of PNM followed by a rapid decline and it becomes gradually smaller as the PNM decreases and the decline levels off. There may be many reasons for the decline, such as living standards and patterns and the quality of perinatal care. It is reasonable to assume that an initial substantial decrease from a high PNM level can be achieved with simple improvements in these respects at relatively low costs and with parallel effects on long-term morbidity. At a later stage, more sophisticated measures and expansive care programs are needed to achieve a further reduction, but these may increase the risks of long-term morbidity-which constitutes the disadvantage of such developments. Risk of CP and birthweight. The risk of CP increases sharply with decreasing birthweight. Fig. 2 shows statistics from Sweden, 1973-76. Similar results are reported from Western Australia and the United Kingdom (4). The liveborn prevalence of CP is 40 times higher in a very low birthweight infant than in one of normal birthwe;ght. Since many more low birthweight infants survive and yet are at a relatively high risk of CP, the overall CP morbidity rate will automatically increase, unless a substantially improved outcome in survivors can be achieved.