OBJECTIVE: To study if pregnant women give the same answers to questions on frequency and timing of binge drinking when asked more than once during and after pregnancy. DESIGN: Cohort study.Setting:The Danish National Birth Cohort. SUBJECTS: The study is based on 76 307 pregnant women with repeated information on binge drinking during the early part of pregnancy and 8933 pregnant women with information on binge drinking during pregnancy weeks 30-36, obtained while pregnant and 6 months after delivery. RESULTS: More women reported binge drinking, if the interview took place close to the period in question. As the report of binge drinking was highest in the first of two interviews referring to the same period, as well as women who participated in the first interview in pregnancy week 12 or earlier reported more binge drinking compared to women who participated in the interview later in pregnancy. CONCLUSIONS: Self-reported information on binge drinking is more frequently under-reported when the recall period is long. To improve the validity of data on binge drinking, future birth cohorts should obtain information several times during pregnancy.
Keywords: Adult; Alcohol Drinking; Cohort Studies; Data Collection; Female; Humans; Interviews as Topic; Postpartum Period; Pregnancy; Pregnancy Trimester, First; Pregnancy Trimester, Second; Self Disclosure; Time Factors