However, the study, published this week, also found that being looked after by grandparents does appear to help develop a baby's vocabulary, particularly for children who also have highly educated mothers.
Researchers suggested this could be because grandparents have more time than other carers to talk to children and are more likely to use grammatically correct sentences and to correct children's language.
The research involved 4,800 children whose mothers all went out to work when they were babies and who are being tracked by the Millennium Cohort Study.
Mothers who took part in the study reported that children cared for by their grandparents had more behavioural problems at age three than those who had been in nursery or looked after by a childminder, nanny or other family member.
The study did not investigate why children in grandparents' care had more behavioural problems, but it highlighted previous studies that suggest that time in pre-school settings can help children develop the social skills to get on with peers.
Co-author Kirstine Hansen said, 'A possible explanation is that grandparents are less mobile and less likely to take children to play sessions.'
Children who had attended nursery were also found to be more ready for school, said Dr Hansen. 'This is almost certainly because nurseries and creches are more likely to offer structure and content to daily activities and their staff are more likely to be trained, to have better facilities and resources and to provide more educational stimulation.'
Further information
'Early Childcare and Child Development' by Kirstine Hansen and Denise Hawkes is in the current issue of the Journal of Social Policy at www.cambridge.org