A strength of this study is the accuracy of the alcohol measure [21] and a focus on the most frequent patterns of drinking, rather than heavy and chronic alcohol consumption. We believe this has played a key role in high participation and low attrition, but most importantly, in providing PAE data of the highest quality possible. Although our study measured PAE prospectively and thus optimised our ability to measure frequency, dose and timing of exposure, the use of self-reported questionnaires runs the risk of reporting bias. However, our focus group research showed that if questions on alcohol in pregnancy are appropriately contextualised and include an option to report unusual drinking episodes, this will encourage more accurate reporting, [21] a finding which appears confirmed with the high number of binge episodes reported in response to the special occasion question.
