The study, published today [20 November] in the journal Child Development, found children who lived with a single mother before age 11 had lower verbal ability than children whose parents stayed together.
Researchers at the University of Bristol, the University of Bath and the Universidad de Alcalá in Spain have shown that, while single motherhood has become much more common, it still has negative consequences for children’s attainment because it reduces the financial resources available to them.
The results show that income, home ownership and parents’ aspirations are associated with higher attainment, while financial hardship and maternal depression are associated with worse outcomes.
Children who lived with a single mother had lower incomes and were less likely to live in owner-occupied accommodation than those whose parents remained together. They found few differences in the parenting behavior of single mothers and those in couples, and this could not explain differences in children’s attainments.
Researchers used data from three large, nationally representative studies of British children born in 1958, 1970, and 2000, each with information on more than 10,000 children. A measure for verbal ability – a good marker for general academic ability - was available for each of the cohorts, allowing changes over time to be examined.
Children's cognitive ability is strongly related to a range of later life outcomes, including the likelihood of dropping out of school, earnings, occupational attainment, crime, substance abuse, and mental health.
For children born in 2000, the age at which their parents separated mattered to their attainment - those whose parents separated before they were seven had lower attainment than their peers in two-parent families. For example, an individual who would have been ranked 50th out of 100 children on the test was instead ranked 44th due to the lower income associated with being raised by a single mother.
But those whose parents separated when they were between seven and 11 showed no significant effect on their attainment. This was because by 2000, the negative economic effects of parental separation were much smaller for those whose parents separated when they were of school age.
This pattern differs from that of children born in 1958 or 1970, for whom parental separation had a similarly negative effect on children's attainment regardless of the age at which their parents separated.
The findings have important implications for policy makers as they suggest supporting the incomes of single-mother families, and in particular those with very young children, would help address the attainment gap.
Susan Harkness, Professor of Public Policy in the School for Policy Studies at the University of Bristol, led the study and said: "Our study shows that almost all of the relationships between single motherhood and negative consequences for children's cognitive attainment can be explained by families’ reduced economic circumstances.
"Although single motherhood has become much more common in the UK, deficits associated with parenting - as opposed to reduced economic circumstances - have all but disappeared over the last 40 years."
Over the last 60 years, the percentage of children in the United Kingdom living in homes headed by a single mother has risen steadily. Between 1971 and 1998 the share of children in single parent families tripled from seven per cent to 22 per cent before stabilising.
The researchers identified few differences in the parenting behaviour of single- and two-parent families for children born in 2000, which wasn’t the case for those born in 1958.
Study co-author Paul Gregg, Professor of Public Policy at the University of Bath, said: "Overall, our findings suggest two policy responses in the UK: supporting the incomes of single-parent families, particularly those with very young children, and addressing the growing gap in attainment between all children whose parents have adverse economic characteristics, whether partnered or not."
The study was supported by the Economic and Social Research Council (ESRC).
'The Rise in Single-Mother Families and Children's Cognitive Development: Evidence from Three British Birth Cohorts', by S. Harkness, M.F. Salgado, and P. Gregg in Child Development.