An analysis of observational studies published in BMJ Evidence-Based Medicine found evidence to suggest maternal caffeine consumption was associated with negative pregnancy outcomes.
The widespread existing advice to pregnant women is consuming a small amount of caffeine – found naturally in food and drinks such as tea and coffee – each day will not harm their baby.
The NHS, the American College of Obstetricians and Gynaecologists and the European Food Safety Authority set this safe level of consumption at 200 mg of caffeine – the equivalent of roughly two cups of moderate-strength coffee per day.
But Professor Jack James, a psychologist at Iceland’s Reykjavik University, said such advice was “not consistent with the level of threat”.
His analysis concluded there was “substantial cumulative evidence” of a link between maternal caffeine consumption and diverse negative pregnancy outcomes such as miscarriages and childhood obesity.
The study carried out a review of current evidence on caffeine-related pregnancy outcomes to determine whether the recommended safe level of consumption for pregnant women was soundly based.
After examining data from 37 observational studies, Prof James found 32 of these studies reported that caffeine significantly increased risk of adverse pregnancy outcomes including stillbirth, miscarriage and low birth weight.
He also cited an increased risk of childhood acute leukaemia and children being overweight or obese when born to mothers who consume caffeine during pregnancy.
The review found evidence for a link in five out of six negative pregnancy outcomes, excluding preterm birth.
“Current advice such as that issued by ... the NHS is not consistent with the level of threat indicated by biological plausibility of harm and extensive empirical evidence of actual harm,” Prof James said.
“Accordingly, current health recommendations concerning caffeine consumption during pregnancy are in need of radical revision.”
He added: “Specifically, the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine.”
Daghni Rajasingham, a consultant obstetrician and spokesperson for the Royal College of Obstetricians and Gynaecologists, said the study added to the large body of evidence supporting only limited caffeine intake during pregnancy, but did not mean pregnant women needed to completely cut out caffeine.
“As the study notes, high levels of caffeine during pregnancy can lead to miscarriage and babies having a low birth weight and may lead to excess weight gain in the child’s early years, which can increase risk of health problems later in life,” Mr Rajasingham said.
“However, as other – and potentially more reliable – research has found, pregnant women do not need to cut caffeine out entirely because these risks are extremely small, even if the recommended caffeine limits are exceeded.”
He added that the Royal College of Obstetricians and Gynaecologists’ recommended limit for caffeine intake (200 mg per day) still stood as before.
Additional reporting by PA
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