Self reported alcohol intake in pregnancy: comparison between four methods

Study objective-To assess the agreement between four different measures of alcohol intake in pregnancy. Design and setting-Danish speaking pregnant women referred to the Midwife Centre in Aarhus, Denmark, for routine antenatal care were contacted at their first visit at approximately 15-16 weeks gestation from October to December 1998. The women were interviewed about current average alcohol intake and intake within the previous week, and subsequently filled in a two week diary on alcohol intake. When booking for delivery at the end of the first trimester the women were also asked to complete a questionnaire including a one item question on current average alcohol intake. Participants-Participants were 441 pregnant women. Main results-Per cent agreement +/-1 category ranged between 73 and 82. Mean (SD) intake ranged between 1.09 (1.35) drinks/week for diaries, and 0.69 (0.85) for questionnaires. Mean differences between methods were all close to zero. Three of the four measures yielded comparable distributions of average alcohol intake, but reports of intake within the past seven days seemed to be an inappropriate measure of average intake, yielding three times as many abstainers as expected when combining the methods. Conclusions-When assessing the distribution of alcohol intake in pregnancy or when studying adverse pregnancy outcomes that are probably caused mainly by sustained exposure it seems that for pregnant women with low to moderate alcohol intake diaries or an average measure from interviews or a simple one item questionnaire may be applied. A measure of intake for the previous week seems to be a relevant measure only when studying adverse pregnancy outcomes that are most probably caused by binge-like exposure.