Too much coffee 'can reduce pregnancy chances' - study

Drinking too much coffee can reduce the chances of a woman with fertility problems getting pregnant, a study has shown.

Doctors in the Netherlands studied the lifestyle factors influencing pregnancy in almost 9,000 women who had struggled to conceive.

They found that drinking four or more cups of coffee or tea a day could reduce the chances of a natural pregnancy by 26%.

The effect of coffee was the same as that of drinking excess alcohol. Being overweight and smoking were both stronger influences.

Dr Bea Linsten, from Radboud University in Nijmegan, followed the progress of 8,669 women who had undergone In-Vitro Fertilisation (IVF) treatment in the Netherlands between 1983 and 1995.

A total of 16% went on to conceive naturally, 45% within six months of their last round of IVF.

Lifestyle factors were studied by asking the women to fill in questionnaires.

The study found that smoking more than one cigarette a day, caffeine consumption, having more than three alcoholic drinks a week, and being overweight all significantly reduced the chances of a natural live birth. A woman’s history of IVF treatment was also important.

Dr Linsten cited the case of a sub-fertile 36-year-old women with three IVF attempts behind her, the last of which had ended in miscarriage.

If the woman smoked, drank too much coffee and alcohol, and was overweight, as measured by Body Mass Index (BMI), the likelihood of her having a spontaneous pregnancy was just 5%. Without those lifestyle hindrances, it was 15%.

Speaking at the annual meeting of the European Society of Human Reproduction and Embryology (Eshre) in Barcelona, Dr Linsten said: “The number and outcome of IVF, smoking, BMI (body mass index) caffeine and alcohol are all factors of influence..

“We have to remind our patients that they may influence their chance of spontaneous pregnancy after IVF with a healthy lifestyle.”

Dietician Fiona Ford, from the Centre for Pregnancy Nutrition at the University of Sheffield in the UK, said: “Whilst the results of this study are interesting, there are evidently limitations to these findings as post IVF patients are a selective group who have already experienced problems with conception. There is nothing within this study that provides a reason to change guidance to patients.”

Zoe Wheeldon, from the British Coffee Association, said: “There is no need to cut caffeine or coffee out of the diet completely, scientific evidence demonstrates that for pregnant women or those trying to conceive up to 300mg of caffeine per day is perfectly safe.

“This is the equivalent of three to four cups of coffee but all sources should be considered when reviewing total daily caffeine intake. Our advice is in line with the overwhelming majority of previous research published in this area.”