High caffeine levels in womb linked to overweight children

Babies exposed to high levels of caffeine in the womb are more likely to go on to be overweight children, a new study suggests.

Any caffeine exposure was associated with youngsters having a higher risk of being overweight before starting school. Picture: iStock

The study, in the journal BMJ Open, concluded that exposure to moderate to high caffeine levels while in the womb is linked to excess weight gain in early childhood.

The research, led by experts from the Norwegian Institute of Public Health, found that children exposed to very high levels of caffeine can weigh 480g more when they are aged eight compared to children exposed to low caffeine levels.

The authors said that their work supports advice to reduce caffeine intake during pregnancy.

NHS choices advises pregnant women to limit their caffeine consumption to no more than 200mg a day.

A mug of instant coffee, on average, contains 100mg of caffeine while a mug of tea has 75mg. Filter coffee has higher caffeine levels with the average mug containing 140mg of caffeine. While caffeine is mostly associated with hot drinks, it can also be found in other products including energy drinks, some cans of pop and chocolate bars.

In the latest study, experts examined data from more than 50,000 Norwegian women and their babies by taking information from dietary surveys conducted in pregnancy and comparing them to child growth measurements, including weight.

Around half (46 per cent) of pregnant women were considered to have low caffeine consumption – less than 50mg a day; A further 44 per cent had a moderate level of consumption – classed as between 50 and 199mg a day; 7 per cent had high levels of consumption of between 200mg and 299mg a day and 3 per cent had very high levels of over 300mg.

The authors compared data from the dietary surveys to information on child body measurements taken at 11 different stages throughout childhood until they were eight years old.

Average, high, and very high caffeine intake during pregnancy were associated with an increased risk – 15 per cent, 30 per cent, and 66 per cent respectively – of “excess growth” during their child’s infancy compared to children born to mothers who had a low caffeine intake during pregnancy.

Any caffeine exposure was associated with youngsters having a higher risk of being overweight before starting school. But the risk only appeared to persist until youngsters were eight if their mother had “very high” consumption in pregnancy.

The authors wrote: “The results add supporting evidence for the current advice to reduce caffeine intake during pregnancy and indicate that complete avoidance might actually be advisable.”