‘The Norwegian Mother and Child Cohort Study’, published in the BMJ Open journal, found that even drinking one to two cups per day could cause these effects.
Researchers at Sahlgrenska Academy, in collaboration with the Norwegian Institute of Public Health, studied information on 50,943 pregnant women.
The results show that children born to mothers who consumed caffeine during pregnancy are at greater risk of being overweight at preschool and school ages.
Verena Sengpiel, associate professor in obstetrics and gynaecology at Sahlgrenska Academy, said: “There may be good cause to increase the restriction of the recommended maximum of three cups of coffee per day. Caffeine is not a medicine that needs to be consumed.”
For the study, children were followed until eight years of age. At the age of five, the share of children who were overweight or obese was five per cent greater in the group whose mothers had the highest caffeine consumption in the study, compared to those whose mothers had the lowest caffeine consumption.
According to the National Food Agency, Sweden, pregnant women should not consume more than 300 milligrams of caffeine per day, which is equivalent to three cups of coffee or six mugs of black tea.
It has not been clearly shown if caffeine is the direct cause of the overweight issue, but the relationship, alone, has caused researchers to encourage increased caution.
Sengpiel added: “In the Nordic countries, coffee is the primary source, while women in, for example, England, receive the greatest amount of caffeine from black tea. If you look at mothers in the younger age group, it comes from energy drinks. We included different sources in the study and found a similar association between caffeine consumption from these different sources and children’s growth.
“Even if more studies are needed before we can say what this finding really means, caffeine is a substance that you can choose to reduce consumption of or completely refrain from during pregnancy.”