Maternal smoking Maternal smoking during pregnancy: a comparison between concurrent and retrospective self-reports Ann Post a,c , Hans Gilljam a,c , Sven Bremberg a and Maria R. Galanti b,c a Department of Public Health Sciences, Division of Social Medicine, and b Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, and c Stockholm Centre for Public Health, Tobacco Prevention, County Council, Stockholm, Sweden Summary Correspondence: Ms Ann Post, Stockholm Centre for Public Health, Tobacco Prevention, PO Box 17533, SE-118 91 Stockholm, Sweden. E-mail: ann.post@sll.se Post A, Gilljam H, Bremberg S, Galanti MR. Maternal smoking during pregnancy: a comparison between concurrent and retrospective self-reports. Paediatric and Perinatal Epidemiology 2008; 22: 155–161. Retrospective reports of smoking in pregnancy are of importance for clinical or scien- tific purposes. Careful analyses of stability and accuracy of recalled behaviour are, therefore, needed. In 1998, the mothers of 2369 pre-teens born in Sweden retrospec- tively reported their smoking behaviour during the first trimester of the index preg- nancy. We matched these reports with those recorded by midwives at the beginning of the index pregnancy, using information from the Swedish Medical Birth Registry. Using this registry as gold standard, the sensitivity and specificity of the retrospective reports containing any smoking were 83.9% and 92.8% respectively, but the sensitivity was low for daily smoking, 56.0%. Of the 222 discordant reports, 19.0% were due to mothers recalling daily smoking which was not reported at the time of pregnancy, and 42% were due to failure to recall smoking reported at the time of pregnancy, while the remaining 39% retrospectively reported occasional smoking, whereas they were registered as non-daily smokers when pregnant. Retrospective recall of pregnancy smoking is fairly stable over time. Keywords: retrospective report, bias, maternal smoking. Introduction Smoking during pregnancy is associated with adverse maternal and fetal outcomes. Some studies also indicate that fetal exposure to tobacco may be causally related to behavioural problems and own tobacco use in later life. 1–3 Therefore, assessment of smoking status of preg- nant women is of paramount importance, and conse- quently should be routinely included in the assessment of obstetric risk. 4 In clinical settings, smoking status is typically assessed through self-report. In countries like Sweden, where a comprehensive Tobacco Act has been implemented since 1993, the prevalence of daily cigarette smoking among pregnant women has been declining steadily. Smoking in early pregnancy decreased by >50% during the 1990s to 10% daily smokers in 2003. 5 In this context, psychosocial factors, such as sense of guilt, may increase the propen- sity for false reports, thus resulting in inconsistencies between self-reported smoking status and biochemical assessments. 6,7 Another important issue concerns the stability of reports of pregnancy smoking with increas- ing time, as retrospective assessment of maternal tobacco use is sometimes necessary, e.g. for research or legal purposes. The aim of this study was to shed light on factors affecting the concordance between maternal self-reports of smoking in early pregnancy and those given several years after the index birth. Methods The BROMS (Swedish acronym for Children’s Smoking and Environment in the Stockholm County) cohort study was started in the Stockholm region in 1998. The study cohort was identified from a random 155 doi: 10.1111/j.1365-3016.2007.00917.x Paediatric and Perinatal Epidemiology, 22, 155–161. ©2008 The Authors, Journal Compilation ©2008 Blackwell Publishing Ltd.