The study, led by experts from the Norwegian Institute of Public Health and published in journal BMJ Open, monitored 51,000 mother and infant pairs in Norway between 2002 and 2008.
The experts 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.
The women were divided into groups dependent on their caffeine consumption.
Caffeine intake of between 0mg and 49mg was deemed low, between 50mg and 199mg average, 200-299mg was high, and over 300mg very high.
The results revealed that babies exposed to high levels of caffeine in the womb weighed up to half a kilogram more by age of eight compared to children exposed to low caffeine levels.
Exposure to any caffeine level while in the womb was associated with a heightened risk of the child being overweight at the ages of three and five years.
But only very high caffeine intake was linked to excess weight gain at eight years.
Children exposed to more caffeine weighed more
On average, children exposed to very high levels of caffeine weighed 480 grams more than children who had been exposed to low levels.
For women in the low caffeine group, equivalent to less than a cup of tea a day, about 11 per cent of their children were overweight by the age of three. In the average group, it was approximately 12 per cent, the high group 14 per cent and the very high group 17 per cent.
The findings appear to challenge current recommendations to only limit caffeine intake while pregnant.
The NHS currently advises women to consume less than 200mg of caffeine a day, citing risks of miscarriage and restricted growth in the womb.
Just so you know what 200mg of caffeine looks like, one mug of filter coffee contains 140mg of caffeine, a mug of instant coffee 100mg, and a cup of tea 75mg.
But caffeine is also found in foods such as chocolate, with around 10mg in a 50g bar of milk chocolate.
As the study was observational, researchers are unable to prove cause and effect, but they believe the results suggest pregnant women should consider cutting out caffeine altogether.
Previous research into caffeine consumption during pregnancy
Previous research has linked caffeine intake to a heightened risk of miscarriage and restricted foetal growth.
There have been a number of health warnings issued to pregnant women of late. Earlier this month mums-to-be who take painkillers during pregnancy were warned that this could affect the fertility of their unborn child in later life.
Previous research found that pregnant women who take Ibuprofen could be unwittingly harming the fertility of their unborn baby girls.
But the new research found that taking painkillers in pregnancy could harm future fertility of subsequent offspring, which would therefore have an impact on boys as well as girls.
Last month it was revealed that around one in 14 women who had babies in 2016 smoked cigarettes during pregnancy.
Read more from Yahoo Style UK: