Tea is linked to birth risks – UCD research

Caffeine raises risk of low birth weight

IT may be a warming comfort during a chat with friends or after a long day, but pregnant women have been warned to be wary of the humble cup of tea. A new study by UCD researchers has highlighted risks to unborn infants’ health from their mothers drinking tea or coffee.

Fears about the potential link between caffeine and birth problems have been raised before, with the HSE, Food Safety Authority of Ireland and the American College of Obstetricians and Gynaecologists warning mothers not to consume more than 200mg a day.

However, the UCD study shows an increased risk of adverse birth outcomes even when mothers’ caffeine consumption is below these levels.

The study, carried out by lead researcher Ling-Wei Chen, postdoctoral research fellow in nutritional and life course epidemiology in UCD, shows a consistent link between both coffee and tea caffeine and adverse birth outcomes.

Mr Chen wanted to know if there is a link between maternal caffeine intake and negative birth outcomes in a population where tea is the main caffeine source. To do so, researchers used data from a sample group of 1,000 Irish women, whose caffeine consumption was recorded during early pregnancy. This was then compared with the hospital records of their newborns to get information on the birth size and gestational age at birth.

Tea was the main caffeine source for 48% of the women followed by coffee at 39%.

The UCD analysis, published in the American Journal of Clinical Nutrition, showed a consistent link between both coffee and tea caffeine and adverse birth outcomes. In the highest caffeine consumption group, the risks of delivering babies with abnormally low birth weight or short gestational age at birth were about two times higher. The results were similar regardless of the caffeine source.

Apart from smaller birth size and shorter gestation, maternal caffeine intake has been linked to other negative outcomes for the child, such as a lower IQ.

In a statement the UCD researchers said, ‘these findings and other study results, are from observational studies’ but they can’t prove that caffeine causes these outcomes, ‘only that there is a link between them’.

‘In order to prove a direct link between caffeine and adverse birth outcomes, further trials would need to take place whereby expectant mothers would be randomly assigned to two different groups, one which would be given caffeine and one which would not. However, to do so might be deemed ethically dubious,’ the report states.

While the amount of caffeine in foods and drinks varies, the average mug of tea contains between 33mg and 75mg, while instant coffee contains 100mg each. Filter coffee contains roughly 140mg of caffeine per cup, while a can of cola contains about 40mg. It is not well-recognised that tea contains a significant amount of caffeine, so its consumption should also be taken into consideration when trying to adhere to the guideline caffeine intake limit during pregnancy, the experts said.

1,000 pregnant women took part

EXPECTANT mothers are already bombarded with medical advice on what to do and what not to do during pregnancy – don’t consume alcohol, avoid soft cheese, eat more folic acid, and so on. It can be a minefield that puts them under pressure and makes them feel guilty if they slip up, and that cannot be healthy either.

That said, new research on caffeine intake during pregnancy bears consideration. Researchers at University College Dublin found drinking more than one cup of coffee a day, or three cups of tea, was a factor in premature births, low birth weight, and even negative impact on the child’s IQ.

No-one wants to be alarmist, but this new advice, dispiriting as it might be for any pregnant woman who enjoys a cuppa, is welcome and vital.