the influence of prenatal events on the development of headaches at childhood has not been investigated and is the scope of our study. of 2,173 children identified as the target sample, consents and analyzable data were provided by 1,440 (77%). parents responded to a standardized questionnaire with a validated headache module and specific questions about prenatal exposures. odds of chronic daily headache (cdh) were significantly higher when maternal tabagism was reported. when active and passive smoking were reported, odds ratio (or) of cdh were 2.29 [95% confidence intervals (ci)=1.6 vs. 3.6)]; for active tabagism, or=4.2 (95% ci=2.1-8.5). alcohol use more than doubled the chance of cdh (24% vs. 11%, or=2.3, 95% ci=1.2-4.7). in multivariate analyses, adjustments did not substantially change the smoking/cdh association. prenatal exposure to tobacco and alcohol are associated with increased rates of cdh onset in preadolescent children.