Two recent studies have linked caffeine with miscarriage. Pat Thomas reveals how the risk increases with the amount of caffeine consumed

Once you become pregnant the number of foods you need to be wary of increases dramatically. Most pregnant women know they should avoid unpasteurised cheese because of the presence of the bacteria lysteria, which can cause listeriosis and put your baby at risk. Liver, shellfish and peanuts are also on the banned list and alcohol should only be consumed in moderation, if at all. Now there’s another item to avoid – and it’s bad news for those addicted to the teapot or wedded to endless mugs of coffee.

A recent American study in the journal Epidemiology, found that women who consumed more than 20 mg of caffeine a day during early pregnancy had a greater risk of miscarriage.
By comparison with women who consumed less than 20 mg:

• Those who consumed 20-99 mg/day (equivalent to a chocolate bar and a cup of instant coffee) were one and a half times more at risk of miscarrying.
• Those who consumed 100-299 mg/day were twice as susceptible.
• Those who consumed more than 300 mg/day had two and a half times the risk.

Women who consumed over 300 mg/day of caffeine and suffered from nausea, were deemed to be five times more at risk of miscarrying.

The research also suggested that caffeine consumption resulted in decreased levels of oestrogen, which while alleviating the nausea – and perhaps encouraging the woman to drink more – may also increase the risk of miscarriage.

The finding of the American study echoed those in a Swedish report published last year in the New England Journal of Medicine.
It found that compared with less than 100 mg/day intake of caffeine:

• 100-299 mg per day was associated with 1.3 times the risk of miscarrying
• 300-499 mg/per day there was a 1.4 times risk
• Above 500 mg/day the risk was 2.2 times greater

The results of these studies aren’t new

A large volume of research has linked daily caffeine consumption (usually more than 150mg) with miscarriage. But no one is yet able to say with certainty how or why caffeine causes miscarriage.

Although the risk may not necessarily apply to all women, it is of particular importance to women who are prone to miscarriage. They may be particularly sensitive to the effects of caffeine and, armed with this information, may feel they would like to try cutting down.

Whether you’re pregnant or not, high consumption of caffeine is not a healthy habit. Physiologically, the side effects can run the gamut from heart palpitations to high blood pressure. It has been implicated in everything from cancer and heart disease to osteoporosis. And while some people find that caffeine gives them a buzz, others say it makes them tense, anxious and headachy.

If you’re interested in cutting down your caffeine consumption there are plenty of alternatives

The most obvious choice is a decaffeinated version of your favourite brew. Green tea is also very low in caffeine, as are herbal teas. Another alternative is herbal coffee made from roasted herbs such as chicory, carob, barley and betel nut, which can be ground and brewed.

Whichever way you choose to go, the key appears to be conscious consumption – if you don’t let caffeine become a habit, it’s unlikely to be a problem.

How much caffeine?

Use the list below to check your caffeine consumption:
Figures for drinks relate to an average cup containing 150ml or ¼ pint.
Figures for chocolate bars are for a small or 125g bar.

Filter coffee 115mg
Instant coffee 65mg
Tea 40mg
Cola 18mg
Cocoa 4mg
Decaffeinated coffee 3mg
Decaffeinated tea 3mg
Dark chocolate 80mg
Milk chocolate 20mg
Two painkiller tablets 60mg