Modern dads are playing a greater role in stimulating their children when mothers return to work early, ensuring that they do not lag behind when they start school.
Researchers have found no evidence of a negative impact on a child's subsequent educational attainment if working mums go back to their jobs within 18 months of giving birth.
This appears to be due to a higher level of involvement in playing with, reading to and singing to their children on the part of the father, as well as the mother sacrificing more leisure time to compensate for her absence.
The study, the first of its kind in the UK, was carried out by Paul Greeg, professor of economics at Bristol University, and Elizabeth Washbrook, a PhD student at Oxford University.
It is based on analysis of data collected on 9,000 babies born in the Avon area in the early 1990s and tracked thereafter through school entry tests, key stage tests at age seven and specially devised literacy and numeracy assessments.
The results, presented at the Population Association of America's annual meeting, suggest that it does not hurt the child for a mother to return to work early and it may even help boost the education of some children if family income is especially low.
Professor Greeg said the key was providing a stimulating environment for the child.
"There is a surprisingly higher level of dad involvement in singing, reading and playing with the kids when the mother is working, and that seems to make a real difference," he said.
"Mothers engage in other compensatory strategies, putting more effort into singing and talking to their kids while cleaning, in order to avoid adverse effects.
"Although the mothers are obviously not there as much, the overall quality time spent teaching or reading to the kids is not suffering."
Professor Greeg said that this usually involved professional child-minding while the parents were at work.
The only negative impact to emerge from the study was if a mother left her child in the care of friends and relatives, often grandparents.
In such cases, the children subsequently went on to do a little less well at school.
"The suspicion is that the children are not being provided with as stimulating an environment - maybe granny is just too tired to pump it out for 40 hours a week," Professor Greeg said.
In the poorest households, there was evidence for a slight benefit in educational attainment if the mother worked, probably due to the higher income helping to provide the child with more toys and books.
Professor Greeg said the results contrasted with US studies that found a small overall negative impact, possibly due to less supportive maternity leave legislation and a lower level of part-time employment.