A new study says babies born to black or Asian mothers have a better nutritional start in life than white infants, because their mothers are less likely to smoke and more likely to breastfeed.

A study of almost 19,000 children born across Britain at the start of the 21st century found the health of young children was affected by their ethnic background.

The Centre of Longitudinal Studies at the Institute of Education in London also found that over the last 50 years, early childhood had changed, with more mothers aged over 30 and more fathers likely to attend a birth.

Heather Joshi, co-editor of "Children of the 21st Century: From Birth to Nine Months", said many of the children from ethnic minority families lived in poor urban areas but were still healthier than their white counterparts.

"Although babies born to minority ethnic mothers were more likely to come from low income families and live in poor areas, they were also more likely to be breastfed and less likely to be exposed to cigarette smoke," she said.

Rosie Dodds, a policy researcher at the National Childbirth Trust, said ethnic minority mothers were more likely to breastfeed for cultural reasons, having seen their mothers and family breastfeed, and because there was more support for the practice among the community.

She added: "The first few months is a very influential time and I would say that breastfeeding and not smoking are two of the most effective things you can do to improve children's health."

Professor Shirley Dex, a co-editor of the study, said the findings showed how the circumstances children are born into had changed.

More than a fifth of babies were delivered by Caesarean section - twice as many as in 1970. And more than a third of first-time mothers were over 30, compared to only eight percent in 1946.

More mothers were in paid work compared to earlier generations. But the family set-up remained traditional, with 85 percent of babies born into families where the parents were living together.

And 93 percent of these fathers were present at the birth, while fathers were present at less than half of births where parents were not cohabiting.

Professor Dex said: "Fashion has changed on this and fathers are now encouraged to be part of the process of antenatal care, through the birth and by taking paternity leave."