Tea for two in pregnancy raises the risk of children being overweight

DRINKING three cups of tea a day during pregnancy increases the risk of having overweight children, a study has found.

Pregnant women who took part in the study and consumed more than 200mg of caffeine a day were more likely to have children that were overweight at preschool and school ages.

The study of 50,000 women, which was carried out by researchers at Sahlgrenska Academy in Sweden in collaboration with the Norwegian Institute of Public Health, was one of the world’s largest surveys of pregnant women.

Its results have prompted Swedish researchers to urge increased caution during pregnancy.

“Caffeine is a substance that you can choose to reduce consumption of, or completely refrain from, during pregnancy,” said Verena Sengpiel, an associate professor in obstetrics and gynaecology at Sahlgrenska Academy.

The study tracked the weight of the children from when they were six weeks old until they were eight years old, and average caffeine intake was assessed at mid-pregnancy. Researchers found that, when the children were five years old, the number who were overweight or obese was 5 per cent greater in the group whose mothers had the highest caffeine consumption.

The NHS advises pregnant women to limit daily caffeine consumption to 200mg, which is the equivalent of three cups of tea or two cups of coffee.

High levels of caffeine can also be found in energy drinks and chocolate. Prof Sengpiel said: “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”.

Prof Sengpiel has said that Sweden should re-examine the advice it gives pregnant women. Sweden’s National Food Agency says pregnant women should not consume more than 300mg of caffeine per day, which is equivalent to three cups of coffee.

“There may be good cause to increase the restriction of the recommended maximum of three cups of coffee per day,” Prof Sengpiel said.

During pregnancy, the body takes longer to metabolise caffeine, which easily passes through biological membranes, including the blood-brain and placenta barriers, resulting in exposure of the foetus.

The study, published in the BMJ Open journal, builds on two other studies of the effects of caffeine on unborn children, which used significantly fewer subjects.

In animal studies, exposure to caffeine in the womb has been followed by excess growth and cardiometabolic disease in the offspring.