US top of single parent league
The United States has the developed world's highest proportion of single parents, with one in four children being raised by one.
Of 27 industrialised countries studied by the Organisation for Economic Co-operation and Development, the US had 25.8% of children being raised by a single parent, compared with an average of 14.9% across the other countries.
Ireland was second (24.3%), followed by New Zealand (23.7%). Greece, Spain, Italy and Luxembourg had among the lowest percentages of children in single-parent homes.
Experts point to a variety of factors to explain the high US figure, including a cultural shift toward greater acceptance of single-parent child rearing.
The US also lacks policies to help support families, including childcare at work and national paid maternity leave, which are commonplace in other countries.
"When our parents married, there was a sense that you were marrying for life," said Edward Zigler, founder and director of Yale's Edward Zigler Centre in Child Development and Social Policy. "That sense is not as prevalent."
The OECD looked at a broad sector of indicators that affected families and children, including childhood poverty, early education and amount of time spent on parental care.
Across the nations examined, pre-school enrolment has grown from 30 to 50% between 1998 and 2007. The average enrolment was 58.2%.
The single parent phenomenon has been occurring over recent decades. The study noted the US and England have higher teenage birth-rates than other countries, partially contributing to the higher single-parent numbers, though the proportion of children born outside marriage was not significantly higher than the other countries.