The first injustice : Socio-economic inequalities in birth outcome

Adverse birth outcomes like preterm birth and infant mortality are unevenly distributed across socio-economic groups. Risks are usually lowest in groups with high socio-economic status and increase with decreasing status. The general aim of this thesis was to contribute to the understanding of the relation between socio-economic status and birth outcomes, focussing on maternal education and class, studying a range of birth outcomes. More specific aims were to investigate the relation between maternal education and infant health, to study the combined influence of maternal childhood and adult social class on inequalities in infant health and to explore the contribution of maternal working conditions to class inequalities in birth outcomes. The studies are population based, focussing on singletons births 1973-1990. During the period under study, educational differences in birth outcomes increased, especially between those with the lowest and highest education. The low birth weight paradox emerged, suggesting that the distribution of determinants for low birthweight infants differs for these groups. Further, an independent association was found between maternal childhood social class and low birthweight and neonatal mortality, but not for postneonatal mortality. Since this was found for the two outcomes closest to birth, this indicates that the association is mediated through the maternal body. Finally, there is a contribution of maternal working conditions to class inequalities in birth outcome. Lower job control, higher job hazards and higher physical demands were all to some degree related to increased risk of the following adverse birth outcomes: infant mortality, low birthweight, very low birthweight, foetal growth, preterm birth, very and extremely preterm birth. Working conditions demonstrated disparate associations with the birth outcomes, indicating a high complexity in these relationships.