Research conducted in 18 industrialised countries, including the UK and Ireland, between 1969 and 2000 found that a ten-week extension in paid leave reduces infant mortality by 2.6 per cent. Over a full year the reduction would be 6.8 per cent.
The exact reason for the relationship is unknown, but may be due to longer periods of breastfeeding and better health care among mothers who do not return to work earlier. The study also suggested that women with longer paid leave take more leave before the birth, reducing the occurence of low birthweight and therefore infant mortality.
However, unpaid leave was not found to have the same protective effect because it may force mothers to return to work earlier.
The study is one of three reports on early maternal employment published in the Economic Journal last week.
A second report, based on data from the United States, also flagged up the link between extended maternity leave and improved child health. Research found that children whose mothers return to work early are less likely to be breastfed, to have regular medical check-ups or to receive all their immunisations.
The US has no national policy providing paid maternity leave and unpaid leave is usually limited to 12 weeks.
The third report examined the impact of working mothers on the cognitive development of 7,000 children born in the UKin 1991 and 1992. Children of full-time working mothers showed better outcomes if they had paid childcare than if they were left solely with relatives or friends.
By the age of seven, children in unpaid full-time care were three months behind their peers in literacy and numeracy tests. But short periods of care by relatives were not found to be damaging.
Professor Paul Gregg from Bristol University, co-editor of the reports, said the studies clearly highlighted the importance of extending paid maternity leave to a year.
He said, 'The research shows modest detrimental effects from leaving children full-time with friends or relatives, probably because the environment can be less stimulating than paid care, with an over-reliance on TV. Perhaps Sure Start centres should engage more with these unpaid carers and provide clubs or drop-in centres to introduce the children to more stimulating environments.'
The reports are published in the February issue of the Economic Journal.
For details see www.res.org.uk.