More than half of all US children will likely live with unmarried mothers at some point before they reach 18, said a study by researchers from the Princeton University and the Harvard University, the US.
The absence of a biological father increases the likelihood that a child will exhibit anti-social behaviour like aggression, breaking rules and delinquency.
"These children are 40 percent less likely to finish high schools or attend colleges," the team noted.
Since 1965, the percentage of children raised by unmarried mothers has gone up significantly among all groups.
"The fact that single motherhood is increasing faster among women with less than a college degree means that children growing up with a single mother are likely to be doubly disadvantaged," said Sara McLanahan from Princeton University.
The official poverty rate in 2013 among all families with children was 40 percent if the family was headed by an unmarried mother and only eight percent if the family was headed by a married couple.
Evidence on the impact of these trends comes from the Fragile Families and Child Wellbeing study which is following a cohort of nearly 5,000 children born in large American cities between 1998 and 2000.
The findings coincide with the 50th anniversary of the controversial "Moynihan Report," a 1965 study by sociologist Daniel Patrick Moynihan that argued that growing up in homes without a male breadwinner led to a life of poverty, unemployment and crime.
Also, the high rate of partner turnover during a mother's peak fertility years means that children now experience multiple men entering and exiting their lives, the researchers added.
"Both the departure of a father and the arrival of a mother's new partner disrupt family routines and are stressful for most children, regardless of whether the father was married to the mother or just living with her," McLanahan pointed out.
Changing the current dynamic will be difficult, the authors wrote.
The study appeared in the journal EducationNext.
