Every day, around 15 000 children under the age of five die from causes that could have been prevented.
But the children of highly educated parents survive more often than others. This statistic applies worldwide, according to a newly published sweeping systematic review in The Lancet.
The mother's level of education is particularly important for her children's survival.
"One year of extra education for the mother is associated with an approximately three per cent reduction in mortality on average," says Professor Terje Andreas Eikemo at the Norwegian University of Science and Technology's (NTNU) Department of Sociology and Political Science. Eikemo heads a research group called CHAIN -- The Centre for Global Health Inequalities Research at NTNU.
This finding points to the great importance of education for girls. An estimated 750 million adults cannot read or write, and two-thirds of these are women.
"The findings provide a strong argument for continuing the effort to ensure that girls complete primary and secondary education, especially now that the pandemic risks setting back progress," says Kam Sripada, a neuroscientist and one of the first authors of the study.
The study is also one of the largest ever to show that the father's education also plays a major role. Here, a child's risk of dying before their fifth birthday was 1.6 per cent lower per year of schooling that the father has.
The group has reviewed previous research in the field, a total of 300 study articles including data at the individual level, from just over three million births.
"We collected all the data and all the articles in all languages that look at parents' education and the importance of child mortality. Our study reviewed the mortality rates at one month, one year and five years," says Professor Eikemo.
The importance of the parents' education becomes more critical as the children get older. The higher the parents' education level, the better their children do on average.
"Good health in children's first five years is important for more than just survival. The brain also develops the fastest in that phase. That's why it's crucial to invest in the school system - from the earliest years all the way through higher education. Good conditions can be transferred from one generation to the next, and the opposite is also true," says Sripada.
Mortality among children under the age of five has halved worldwide since 1990, as a result of international, national and local efforts.
But infant mortality rates vary greatly from country to country. In developing countries, just over ten per cent of children die before the age of five. In Norway, the percentage is 0.3 per cent. The global average is now just under 5 per cent.
The main reasons for children dying before the age of five are premature birth, pneumonia, various infections, diarrhoea, malnutrition and malaria, in addition to various complications during and immediately after birth.
The causal relationships are complicated. Level of education, for example, is related to both income and social status, which in turn is related to factors such as lifestyle and access to health services.
"There may be various factors that explain the findings in our study. Parents' health literacy, health-seeking behaviours and consanguanity are among the potential links between parents' education and child mortality," says Sripada.
The researchers found no limit to where the benefit of more schooling flattened out. The more education, the better.
"We didn't find any flattening where more education means less. Every year of extra education gives an increased chance of survival," Eikemo says.
Researchers also were able to see the benefits of education when they adjusted for socio-economic status, which more or less overlaps with the more politically charged concept of social class.
"Rich countries have less infant mortality, but also in these countries it's linked to parents' education," says Eikemo.
The study focuses attention on the connection between social inequalities and health.
"This is a scientific breakthrough. It is the result of fantastic team work from multiple intersecting disciplines," says Eikemo.
The University of Washington Institute for Health Metrics and Evaluation (IHME), Princeton University, the University of California Los Angeles, the Norwegian Institute of Public Health, and the RAND Corporation think tank have been involved in the work. The NTNU participants were the Faculty of Social and Educational Sciences, the Faculty of Medicine and Health Sciences and the NTNU University Library.