Mothers who are unhappy at work, or who are left emotionally exhausted, can pass their stress on to their children, but this can be alleviated if children spend longer in daycare, it found.
The report, published this week in the Journal of Developmental Psychobiology, says that greater support is needed for mothers to help improve their working lives and increase the availability of affordable childcare.
Researchers from Bristol, Bath and Kent universities examined the levels of the stress hormone cortisol by taking saliva samples in the morning and evening from 56 children aged three to four.
They also questioned mothers about their workplace conditions and home life over six months.
The tests revealed that in children whose mothers had low job satisfaction, levels of cortisol in the evening were more than double those of children whose mothers said they enjoyed their jobs.
Cortisol secretion rises in response to physical stress, such as illness, and psychological stress. It is a normal and essential response for functioning in everyday life, but if levels become disrupted or remain high over time, health may suffer.
Dr Julie Turner-Cobb from the University of Bath said, 'Spending more time in childcare makes a big difference to the stress levels in children whose mothers have low job satisfaction. It can help protect children from the effects of their mother's low job quality and emotional exhaustion.
Ensuring that mothers of young children have good support in the workplace is essential for both mothers and their children.'
Dr David Jessop from the University of Bristol said, 'Improving the job satisfaction of working mothers means that they are less stressed themselves, and extending the availability of affordable and adequate childcare may not only improve the quality of life for mothers, but in doing so may improve the long-term health of their children.'
However, research into cortisol in young children published in September by the universities of Cambridge and Berlin found that cortisol levels doubled in children during the first nine days of childcare without their mothers present, and advised that nurseries should let mothers stay at nursery during the first week to help reduce stress for the children.
