Sydney: Intelligence really begins in the womb which shows up as improved numerical ability and literacy skills in early primary school, according to a new study.

The study shows that healthy fetal growth not only helps improve a child's performance, but may contribute towards closing the achievement gap for children from disadvantaged socio-economic backgrounds.

Director of Perth's Telethon Institute for Child Health Research and study co-author Fiona Stanley said the findings reinforce the need for better integration of health and education policy and services.

"This is an example of the need for joined up thinking; that the pathways into improved education include maternal and child health," Stanley said.

"We know that drugs like alcohol and tobacco restrict a baby's growth in the womb so we really need to be supporting mothers and giving them the information they need to have healthier pregnancies."

The study was based on results from more than 55,000 children.

"This is the first time that we've been able to match birth and educational information and identify some of the broad factors that are linked to educational success," she said.

Stanley added that the findings should not alarm mothers who had difficult pregnancies.

These findings were published in the Journal of Epidemiology and Community Health and the American Journal of Epidemiology. IANS