The UK Food Standards Agency has commissioned a study of the possible association between maternal caffeine consumption and low birthweight by the Universities of Leicester and Leeds in the UK
The Agency said it has commissioned the study to reduce uncertainties in the current risk assessment and provide a more robust basis for the Agency's advice to pregnant women on caffeine consumption.
In October 2001, the Agency advised that pregnant women should limit their caffeine intake to the equivalent of no more than four average cups of coffee a day. The advice was based on the opinion of the Committee on Toxicity (COT) on the reproductive effects of caffeine.
Unlike much of the previous research into the possible effects of caffeine on reproductive health, the Agency say its new study is a prospective study that includes biomarkers of caffeine intake and explores inter-individual variations in caffeine metabolism.
In addition it will consider all sources of caffeine intake, not just tea and coffee. The study, which forms part of the Agency's Risk Assessment Programme, started in January 2003 and is planned to report at the end of March 2006. It involves a consortium between the Universities of Leeds and Leicester.
It will investigate a total of about 3,000 pregnant women of which it is estimated that about 300 (10 per cent) will deliver low birth weight babies.
Caffeine consumption from all sources will be assessed by a questionnaire (including a three day food-and-drink diary) and will be validated by measurement of caffeine and caffeine metabolites in urine and saliva at different stages during the pregnancy. Subgroups consisting of 300 women who delivered low birth weight babies and 300 with babies who fell within the normal range of birthweight will also be assessed for both caffeine consumption and metabolism.
Dr Cooke, head of the Leicester team from the Department of Clinical Biochemistry, said: "A lot of people think that, given the large number of studies examining caffeine intake in pregnancy, safe limits should have been determined long ago. However, many of these studies contain clear methodological short-comings preventing bodies, such as the Food Standards Agency, giving precise advice. Our study is designed to overcome these limitations."
"This multi-disciplinary study brings together experts in biomonitoring, public health, epidemiology, nutrition, obstetrics and midwifery," he added.
"The size of the study requires recruitment of women from three of the country's largest maternity units."