Researchers at Boston College found that children from low-income families had slightly higher cognitive skills if their mothers went back to work before they were nine months old.
These toddlers also had fewer behavioural problems if their mothers began work when they were between nine and 24 months old.
For children in middle-income households, there were no ill effects if their mothers worked when they were babies.
However, for children in high-income households, the study found small detrimental effects across all ethnic groups.
The results, published in the journal Developmental Psychology, contradict a large body of preview work of children born two to three decades ago.
‘Mums going back to work when children are still babies may affect the children differently in contemporary society because there are so many more working women today with greater responsibility for their families’ income,’ said lead author Caitlin McPherran Lombardi.
‘Different cultural attitudes, more readily available and higher-quality child care and more fathers participating in childrearing are other possible reasons for the difference.’
The study used data from a National Center for Education Statistics longitudinal survey that followed 10,700 children born in the United States in 2001.
For the more recent survey, 31 per cent of mothers reported no employment in the two years following the child’s birth, while 58 per cent of mothers were employed before the child was nine months old.
Meanwhile, just over 10 per cent were employed when their child was between nine and 24 months.
‘Most mothers today return to full-time work soon after childbirth, and they are also likely to remain in the labour market five years later, suggesting the employment decisions soon after childbirth are pivotal to determining mothers’ long-term employment,’ said Dr Lombardi.
‘Our findings suggest that children from families with limited economic resources may benefit from paid maternal leave policies that have been found to encourage mothers’ employment after childbearing.’
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