Maternal Education as a Modifier of the Association between Low Birthweight and Infant Mortality

Both low birthweight (LBW) and infant mortality rate (IMR) have been consistently shown to be associated with maternal level of educational attainment. This paper examines the mortality risk attributable to LBW in different levels of maternal education. Comprising the study population were 18,715 singleton live births to Jewish mothers ages 20-39, during the years 1977-1980 in the Negev (the southern part of Israel). Data were obtained from a linked record of birth and death certificates. As expected, proportions of LBW (less than 2500 grams) were inversely related to level of maternal education (12.2% in the lowest educational level, 7.9% and 8.0% in the two intermediate levels, and 7.2% in the highest educational level). The mortality risk attributed to LBW was found to be modified by maternal level of education. Mortality ratios standardized for maternal age and parity were computed, using educational level 3, where the lowest mortality rates were observed, as the standard population. Among LBW infants no significant differences were found across educational levels, except for the lowest educational level where only 69% of the expected number of deaths were observed. The survival advantage of LBW infants in the lowest educational level was observed both in the neonatal and the postneonatal periods. Among normal birthweight (NBW) infants, a statistically significant excess mortality was detected both in the highest and the lowest educational levels. The excess mortality of NBW infants in the highest level of maternal education was due to neonatal mortality (SMR = 2.2), while the excess mortality in this birthweight category in the lowest educational level occur mainly in the postneonatal period (SMR = 2.4).(ABSTRACT TRUNCATED AT 250 WORDS)