Researchers looked at the link between caffeine intake during pregnancy and the weights of children up to the age of eight.

London - Women who drink just two cups of coffee a day while pregnant risk their children being overweight, a study has found.

Babies exposed to moderate or high levels of caffeine in the womb have a higher chance of being overweight in early childhood, the research says.

Researchers looked at the link between caffeine intake during pregnancy and the weights of children up to the age of eight.

Studying 51 000 mother and infant pairs in Norway between 2002 and 2008, they measured the expectant mothers’ daily intake of caffeine – found in chocolate, tea and many soft drinks as well as coffee – at 22 weeks of pregnancy. 

More than four in ten were classed as having an average caffeine intake, consuming the equivalent of up to two cups of coffee a day, while 7 percent were classed as high intake (up to three cups) and 3 percent were considered to have a "very high" intake (three or more cups). Just under half of the mothers-to-be were classified as low caffeine intake, consuming the equivalent of half a cup of coffee.

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Their children’s weight and height were then measured at six weeks old, at three, six, eight, 12 and 18 months old, and then at two years and every year up to age eight. 

Those whose mothers had been classed as average caffeine consumers were 15 percent more likely to be heavier – but not taller – than those whose mothers avoided caffeine, the researchers found. 

This correlation grew to 30 percent among the children of high caffeine consumers, and 66 percent among the children of very high consumers, according to the study in medical journal BMJ Open.

Children of very high caffeine consumers weighed up to three ounces more between three and 12 months, rising to a pound more at age eight.

But Professor Jean Golding, of the University of Bristol, said: "It will be important to determine whether any effects of high maternal caffeine intake are apparent at later ages, or … confined to the pre-puberty ages."