Drinking a large amount of caffeine every day can increase a woman's risk of miscarriage, research shows.
A study of 1,063 pregnant women found that those who drank two or more cups of coffee a day had twice the risk of miscarriage as those who drank none.
Lead researcher De-Kun Li said: "This 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."
Women who drank coffee every day but did not drink as much as two cups still had a 40% increased risk of miscarriage in comparison to those who drank none.
The researchers suggest that caffeine may influence cell development and decrease plancental blood flow.
Li adds: "The main message for pregnant women from these findings is that they probably should consider stopping caffeine consumption during pregnancy because this research provides clearer and stronger evidence that high doses of caffeine intake during pregnancy can increase the risk of miscarriage."
The British Coffee Association have stuck to their recommendations that the upper caffeine limit for pregnant women is 300mg per day.
Zoe Wheeldon from the British Coffee Association said: "Whilst this study by Weng et al is a well designed, robust cohort study, this evidence must be reviewed in conjunction with existing research and it is important to review all the available data rather than taking one study in isolation."