Drinking coffee while pregnant isn't as dangerous as previously thought, study suggests

It's a substance pregnant women have been urged to avoid for years.

But coffee, a staple of bleary-eyed office workers and commuters around the world, could be safer for expectant mothers than previously thought, a study on tens-of-thousands of women and their children suggests.

The discovery runs contrary to previous research and years old advice from the NHS, either urging women to limit their intake of coffee's stimulant caffeine, or to avoid in entirely.

One leaflet handed out to pregnant women by the health service starkly warns 'a mug of coffee a day roughly doubles the risk of having stillbirths' adding there 'is no known safe level of caffeine'. 

Yet, the study by led Australian researchers suggests some of these caffeine fears are overblown and not backed up by strong evidence.

However, they added that women should still follow guidelines from officials on daily caffeine intake limits. 

Scientists, from the University of Queensland examined data from tens-of-thousands of Norwegian families.

They chose this group due to both Scandinavians general love of a cup of joe and, in comparison to the UK, a lack of stigma in pregnant women and drinking coffee. 

Experts analysed both genetic data from the families as well as questionnaires on coffee consumption during pregnancy.

They also interviewed parents on their child's development in a bid to explore any potential link with drinking coffee in pregnancy and an impact on their social motor and language skills up the age of eight years. 

But Dr Gunn-Helen Moen, an expert in molecular bioscience at Queensland, said no such affects were observed. 

'Our analysis found no link between coffee consumption during pregnancy and children's neurodevelopmental difficulties,' she said. 

This runs contrary to previous research that linked expectant mothers consuming caffeine could lead to children having developmental delays. 

Dr Moen said previous research on the subject had been unable to unpick if caffeine was to blame for these issues as opposed to other potential factors that can impact the foetus in pregnancy — such as alcohol or tobacco consumption or poor diet.

However, she claimed the team's study, published in the journal Psychological Medicine, avoided this by using genetic screening of participants to find those most likely to be coffee drinkers. 

'It mimics a randomised controlled trial without subjecting pregnant mothers and their babies to any ill effects,' she said. 

'The benefit of this method is the effects of caffeine, alcohol, cigarettes and diet can be separated in the data, so we can look solely at the impact of caffeine on the pregnancy.'

Previous research by the team has also suggested that that drinking coffee in pregnancy doesn't affect birth weight, risk of miscarriage or stillbirth, contrary to NHS advice.

They hope their research can be followed up with further work to explore what factors in pregnancy actually causing developmental differences in children.

The dangers posed by caffeine in pregnancy are linked to physiological changes that occur in a woman's body while a foetus is developing that prevent the stimulant from breaking down as easily as before.

This can lead it to accumulate in the body more than usual and pass via the placenta to the foetus which cannot process it. 

As such the NHS advises pregnant women to limit themselves to 200mg of caffeine a day, equivalent to two cups of instant coffee.

To keep within this limit, expectant mothers also need to watch out for other sources of caffeine, such as teas, soft and energy drinks, as well as chocolate.

UK guidelines, which are replicated in the US, on caffeine intake during pregnancy are stricter than the international standard.

The World Health Organization's recommendation is for women to reduce their intake to less 300mg a day.

Research on the impact on coffee, or more specifically caffeine, in pregnancy has usually found negative effects.

Earlier this year, Chinese research linked coffee intake in pregnancy to an increased risk of autism in children, based on experiments on rats.

Previous research has also linked coffee consumption to knocking almost an inch of children's potential height with experts theorising this results from the stimulant constrict blood vessels that feeding the developing foetus.