Premature babies earn less as adults, possibly due to lower maths ability

02 September 2015

People who are born premature tend to accumulate less wealth as adults, and a new study funded by the Nuffield Foundation suggests this may be due to lower mathematics abilities. The findings, published in Psychological Science, a journal of the Association for Psychological Science, show that preterm birth is associated with lower academic abilities in childhood, and lower educational attainment and less wealth in adulthood.

“Our findings suggest that the economic costs of preterm birth are not limited to healthcare and educational support in childhood, but extend well into adulthood,” says psychological scientist Dieter Wolke of the University of Warwick in the UK. “Together, these results suggest that the effects of prematurity via academic performance on wealth are long term, lasting into the fifth decade of life.”

Researchers examined data from two large, longitudinal studies: the National Child Development Study and the British Cohort Study. Both of the studies recruited all children born in a single week in England, Scotland, and Wales, and researchers have followed up these children through to adulthood.

Importantly, the studies follow individuals born more than a decade apart: the National Child Development Study follows children born in 1958 and the British Cohort Study follows children born in 1970.

Wolke and colleagues specifically examined data for all individuals in the studies who were born at between 28 and 42 weeks gestational age and who had available wealth information at age 42, yielding a total sample of over 15,000 participants.

To measure adult wealth, the researchers looked at a combination of participants’ family income and social class, their housing and employment status, and their own perceptions of their financial situation. To gauge participants’ academic abilities, they examined a combination of validated measures for mathematics, reading, and intelligence, combined with ratings from teachers and parents.

The researchers also accounted for several variables that might otherwise influence outcomes in childhood and adulthood, including birth weight, maternal prenatal health, and parental education and social class.

The results were revealing: In both of the cohorts, children who were born preterm tended to have lower wealth at age 42 and lower educational qualifications in adulthood than those who were born full-term. Individuals born preterm were more likely to be manual workers, more likely to be unemployed, more likely to report financial difficulties, and less likely to own a house than those who were born full-term, even after other potential factors were taken into account.

As predicted, preterm children also tended to demonstrate lower academic abilities in childhood, and for mathematics in particular. And the link between preterm birth and academic abilities in childhood helped to account for, at least in part, the link between preterm birth and wealth in adulthood.

“What is perhaps most surprising is that most of the children we studied were not very preterm—born, on average, only 5 weeks early — and still we find these long lasting effects,” says psychological scientist Maartje Basten, a co-author.

While the overall size of the effects observed in the study are small, the fact that these effects emerge at all after four decades is remarkable, the researchers argue. They note that the rate of preterm births has increased in recent years, and data from children born in just the last decade indicate that preterm birth continues to be a risk factor for decreased cognitive functioning and lower academic achievement.

“Our previous research has shown that teachers and educational psychologists receive no training on needs of preterm children. They have little knowledge of the specific difficulties that preterm children have with learning and attention,” says Wolke. “Providing this knowledge and developing appropriate interventions could make a big difference for many preterm children and improve their life chances.”

Co-authors on the study include Maartje Basten of the University of Warwick, Julia Jaekel of the University of Tennessee and Ruhr-University Bochum, Samantha Johnson of the University of Leicester, and Camilla Gilmore of Loughborough University.