Is coffee safe to drink in pregnancy?

A US study has revealed that pregnant women drinking more than two cups of coffee a day are doubling their risk of a miscarriage, according to recent reports in the press.

US research findings suggest that current guidelines regarding caffeine intake during pregnancy should be revised.

The Food Standards Agency (FSA) recommends that pregnant women should not consume more than 300mg of caffeine a day.

However, in light of the new evidence, some experts have suggested women should avoid caffeine completely during the first 12 weeks of pregnancy.

What is the research?
The media focused on a study of 1,063 pregnant women recruited in San Francisco over two years.

Importantly, the researchers tried to eliminate any confounding factors, which have clouded previous studies into caffeine and miscarriage. For example, controls were put in place to account for 'pregnancy-related caffeine aversion'.

Additionally, a questionnaire gathered information on a host of other potential confounding factors such as maternal age, alcohol consumption and exposure to magnetic fields.

Participants' daily caffeine intake from a range of drinks was also calculated.

The pregnancy status of every woman in the study was determined up until 20 weeks' gestation. During this time, 172 women miscarried.

Women consuming up to 200mg of caffeine a day were 42 per cent more likely to miscarry than those not consuming caffeine at all.

Those who had more than 200mg, the same as two cups of coffee or five cans of cola, had twice the miscarriage risk of non-consumers.

What do the researchers say?
Dr De-Kun Li, led the research for US health insurance company Kaiser Permanente.

'The study strengthens the association between caffeine and miscarriage risk because it removes speculation that the association was due to reduced caffeine intake by healthy pregnant women,' she said.

In light of the results, Dr Li thinks pregnant women should 'consider stopping caffeine consumption'.

Dr Tracey Flanagan, director of women's health at Kaiser Permanente, said that 'natural energy boosts' such as a brisk walk, yoga stretches or snacking on dried fruit and nuts may be more suitable ways to keep alert during pregnancy.

What do other experts say?
Mr Pat O'Brien, consultant obstetrician and spokesman for the Royal College of Obstetricians and Gynaecologists, was supportive of the study saying the research used 'decent numbers' and was 'well controlled' for confounding factors.

He therefore said the findings would change the advice he gave to patients: 'I will tell them to avoid caffeine as much as possible in the first 12 weeks of pregnancy.'

Mr O'Brien believes that the FSA guidelines will adapt to reflect a similar message.

Informing patients

  • Research has shown that consuming 200mg caffeine daily can double miscarriage risk.
  • Two cups of coffee or five cans of cola contain 200mg caffeine.
  • Current FSA guidelines say pregnant women can drink up to 300mg daily.
  • Leading obstetrician says caffeine guidelines need revision.

GPletters@haymarket.com

Am J Obstet Gyn Online 2008

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