Differences In Neonatal Mortality Research Articles

Infant Mortality-Reply

In Reply.— Variation in the extent to which live infants of very low birth weight are recorded accounts for only a small proportion of international differences in neonatal mortality. Where these infants are not recorded as live births, they are generally recorded as stillbirths, and as both Norway and Sweden have lower stillbirth rates than the United States, this particular classification problem cannot explain the Scandinavian advantage in perinatal mortality. The birth weight distribution for white persons in the United States is, moreover, more unfavorable than that of Sweden and Norway, even if infants weighing less than 1,000 g are not considered. International comparisons of infant mortality will not go away if we ignore them. What is necessary is that these rates be interpreted sensibly.

Low Birth Weight and Perinatal Mortality

A RECENT STUDY by the National Center for Health Statistics, Public Health Service, was concerned with the higher and more slowly decreasing perinatal and infant mortality in the United States compared to six West European countries, one of which was Sweden (1). In 1964 the U.S. infant mortality rate was highest among the seven countries and 75 percent higher than the lowest rate, that for Sweden. Even when the comparison was limited to white infants in the United States, the rate was 52 percent higher than in Sweden. In each of the countries studied, the decline of both infant and perinatal mortality was retarded after 1950, but the slowing down was more evident in the U.S. rate than in all but one of the others. According to the Public Health Service study, the differences cannot be explained by factors such as age of the mother or birth order of the child. The data show that the incidence of low-birth-weight infants is higher in the United States and that it has been slowly increasing. The data also suggest that differences in birth weight distribution could account for as much as 85 to 90 percent of the differences in neonatal mortality between the United States and Sweden. The comparison is hampered, however, by insufficient data on birth weight from the European countries and by lack of U.S. data on weight-specific mortality rates later than 1950.