Mothers’ level of education and infant health. Causal effects of the introduction of a school reform in Norway

We estimated the effects of mother's level of education on infant health by using data from a school reform in Norway. During the period 1960–1972, all municipalities in Norway were required to increase the number of compulsory years of schooling from seven to nine years. This reform was used to create exogenous variation in the education variable. The control group comprised children who were born too early to have been exposed to the reform. The treatment group comprised children in the same municipality who were born late enough to have been exposed to the reform. The education data were combined with data from the Medical Birth Registry of Norway. We carried out analyses with several infant health outcomes: foetal, neonatal and infant mortality, mortality at the age of five or earlier, low birthweight, preterm birth and Apgar score. We found no effects of education on foetal and neonatal mortality, but significant effects for the other outcomes. The mother's level of education influenced the health of her infant through several channels, such as her health status, marital status, spousal education and income. We carried out several robustness tests, which supported our main results.