For some time there has been a suspicion that coffee is harmful to the unborn baby. Most research on the topic is of rather dubious quality. It is, after all, difficult to be sure about how much women have genuinely consumed (although blood levels of caffeine have been used to confirm diary records) and probably more importantly there may be other factors at play.
We know that women with a high caffeine intake differ from those with low or no caffeine use in many ways. As the latest report in the British Medical Journal (26 January 2007) put it: [women with higher coffee consumption] smoke more, have higher alcohol intake and have attained a lower level of education. These are all independent risk factors for the kind of pregnancy outcomes that we are interested in and worry about, such as miscarriage, premature birth and low birthweight babies.
In early pregnancy there is evidence that higher intake of coffee can almost double the chance of miscarriage, but this is only if you are taking 5 or more cups per day (equivalent to 500mg of caffeine). One or two cups per day is not linked with miscarriage.
This week's study looked at 1200 Danish women who were drinking more than 3 cups of coffee per day. The researchers gave half of the women decaffeinated coffee to have instead, starting from mid-pregnancy. Total coffeine intake for those who received decaf was overall the equivalent of 3 cups of coffee less than those who carried on as before.
No difference was found between the two groups of women in terms of likelihood of premature labour or having a low birthweight baby. This suggests that switching to decaf is unlikely to have any particular benefit if you drink more than 3 cups per day.
The study wouldn't be expected to pick up differences if reducing coffee earlier than mid-pregnancy was important or if greater reductions were necessary.
Approximate caffeine intake from common drinks is as follows:
Cup of coffee: 100mg
Mug of coffee: 200mg
Cup of tea: 50mg
Glass of cola: 20mg
This study is important as they did check for other factors mentioned above that are known to be associated with premature labour and growth problems. Also, the fact that it is a randomised, planned intervention study makes it more likely to be accurate (as compared to research that analyses population statistics).
It is my recommendation that pregnant women drink no more than 3-4 cups of coffee per day in early pregnancy and to probably limit it to less than 5-6 cups in later pregnancy, recognising that we still don't have complete data to inform us of the exact risks.
Comments