While the effects of caffeine consumption on the human body have been hotly debated by scientists over the years, the growing mountain of data to support the harmful effects of the stimulant on expectant mothers, particularly during the first three months of pregnancy, and the foetus is difficult to ignore.

The generally accepted limit on caffeine consumption for preganant women ranges from 150mg/day to 300mg/day, the British government caps it at 300mg. However, the latest study goes beyond this, stating that even 200mg can have an adverse effect on the chances of a safe pregnancy.

The study conducted by Kaiser Permanente researchers and published in the current issue of the American Journal of Obstetrics and Gynaecology monitored 1,063 pregnant women. The study showed that those who had at least 200mg (approximately two mugs of coffee) of caffeine each day ran twice the risk of a miscarriage than women who cut down on all caffeine-loaded products, such as coffee, tea, colas and chocolate.

The women's diets were monitored until the 20th week of gestation: 635 had up to 200mg a day; 164 women had 200mg or more daily; and 264 had none. Mothers-to-be who adopted a caffeine-free diet ran a 12 per cent risk of miscarriage, while those who continued to consume caffeinic products ran a 25 per cent risk.

The study took into account other factors known to affect the risk of miscarriage -- smoking and alcohol consumption, age, income, and medical history.

Studies conducted by various health NGOs worldwide during each trimester of pregnancy have revealed similar results, however, the limit continues to fluctuate as empirical data continues to vary. Although, the basic premise, that caffeine does adversely affect the foetus and increases the risk of a miscarriage, remains as doctors continue to recommend cutting back on that daily fix of coffee during pregnancy.