Researchers who monitored the attendance of 139 white children at five of the city's primary schools found that pupils with mothers in full-time jobs were off for three days on average over two terms. Children with mothers in part-time work had 5.35 days off, those with mothers at home had 6.67 days.
But Therese Dowswell and Jenny Hewison, of Leeds University's psychology department, say that these discrepancies cannot be attributed to the fact that the children of full-time working mothers have to be more ill before they are kept away from school, or that mothers at home allow their children to stay off for trivial illnesses.
They say that their research did partly substantiate this theory - they checked detailed information about the children's coughs and colds against a severity measure originally devised for a study of doctor consultation behaviour. But it revealed that the children of full-time working mothers also had fewer bouts of severe illness.
This would be unsurprising if these mothers were members of affluent families, but in fact their social status was not markedly different from the mothers who worked part-time or stayed at home, they say in a paper published in the British Educational Research Journal.
The researchers point out, however, that it is possible that mothers and children who are prone to recurrent or serious illness (for example, asthma) may have selected themselves into the 'at home' or part-time groups.
And they caution that absence is not synonymous with sickness. "For almost half the sample, reasons other than the severity of the child's condition were used to justify decisions to keep a child away from school.
"In some cases the environment of the school was perceived by parents as not being the most conducive to recovery. School was portrayed as too hot, too cold, too noisy or stuffy even for the child that was only slightly unwell . . . and sometimes it was perceptions about teachers' attitudes alone rather than the child's needs or condition that were used to justify absence."
Society should be more understanding of the problems that child health care creates for working mothers, Dowswell and Hewison argue. "You can't keep taking time off," said one mother whose child had repeated bouts of tonsillitis. "I feel guilty because I am not doing my job and I'm guilty because I can't stay home. When I get up my heart sinks if she says she is ill."
They note that in the UK there is no legal entitlement to time off from work to care for a sick child, or for other family reasons such as to attend a school open day.
Other European countries have more humane arrangements, and Swedish parents are allowed up to 60 days' leave each year for family responsibilities.
"The final irony is that until official and personal attitudes change towards working mothers, the women who bear the costs and make the sacrifices needed to perform the act of juggling work and family responsibilities to provide their children with the best possible health care may still be regarded as those very women who 'skive off' work," Dowswell and Hewison conclude.
"They may also be perceived by non-working mothers, and possibly teachers, as the uncaring group who 'send' their 'sick' children into school. It is surely time that the provision of child health care moved out of the home and into the arena of public policy and debate."
The British Educational Journal, Carfax Publishing Company, PO Box 25, Abingdon, Oxfordshire 0X14 3UE.