Yet another health scare for women hit the news last week. This time it was how much coffee they should drink, if any, when they are pregnant.

The headlines issued dire warnings about damage done to infants in the womb when their mothers drank coffee. That was far from the message that the researchers who did the study wanted to be made public, and has had the effect of frightening women who have drunk coffee and now think they may have harmed their babies.

So let’s look at the study and see what it really means for pregnant women. It was performed in two hospitals in Leeds and Leicester, and 2,635 pregnant women with normal pregnancies, considered to be at low risk for any abnormalities, took part.

They started on the trial between the eighth and 12th week of their pregnancies, and were asked first to estimate how much total caffeine they had drunk each day in the four weeks before conception and then throughout their pregnancies.

Their babies were then weighed at birth, and the weight related to the amounts of caffeine that they had consumed. Their saliva was tested for the amount of caffeine in it, and for cotinine levels (a measure of their exposure to tobacco), and their alcohol intake was also noted.

The results? The more caffeine the women had drunk, the smaller their babies were at birth. This link was true after taking into account their alcohol and tobacco habits.

The advice given by the researchers? That women should take in as little caffeine as possible if they are trying to conceive, and also when they are pregnant.

Sounds great advice, but I have some misgivings.

First, only 13 per cent of the women actually had smaller-than-expected babies – 343 out of the 2,635 pregnancies. The study does not mention that any of the babies were harmed: there is no evidence given that the lower birth weight (of only 60 to 70 grams in the women taking the most caffeine) had caused any illness in, or damage to, the babies. Caffeine is not simply present in coffee alone. Tea accounted for 62 per cent of the caffeine the women had drunk: coffee accounted for only 14 per cent, cola drinks for 12 per cent, and chocolate eight per cent. So the advice on cutting down on caffeine would mean that women should stop eating or drinking all of them. For many women there is little left.

So how should GPs like myself advise pregnant women who might have been alarmed by this study?

By all means don’t overdo the drinks containing caffeine – but you don’t have to go without. There are plenty of studies to show that two or three cups of tea a day are unlikely to cause a problem.

And if you do want to cut down on the caffeine, don’t turn to other drinks, say containing alcohol, or large amounts of sugar, instead.

The fact that most of the women in the study got their caffeine from tea, rather than from coffee, was curious. Several studies have shown that drinking tea while pregnant has no effect on the growth of the developing baby, so there is a contradiction here.

There is no doubt that caffeine does cross over from the mother’s circulation into the baby, so that overdoing the coffee and tea will expose the baby to it.

Drinking an excess of coffee and tea does come with other lifestyle habits, like smoking and alcohol consumption.

In the one study that compared the effects of drinking full-strength coffee and decaffeinated coffee, there was no eventual difference in the baby’s weights at birth, except when the mothers drinking the coffee with the caffeine in it also smoked. We can’t yet explain these differences.

To summarise: if you are pregnant, it’s best to drink only a little tea and coffee each day, and to avoid smoking and alcohol – they are much worse for you and your baby.

And please don’t worry if you are pregnant now and have been drinking lots of tea and/or coffee. Cut down by all means, but don’t worry that you have harmed your baby. From the evidence so far, it is extremely unlikely that you have.