Objective: To determine the prevalence of headaches and their influencing factors among pregnant women. Methods: A cross-sectional study was conducted from January 3 to April 29, 2005, with 1357 women receiving routine pregnancy check-ups at the obstetric clinics of the community health institutions of Kayseri, Turkey. A structured questionnaire and the Zung Depression Scale were used to collect data. Results: Overall, 24.6% (95% confidence interval, 22.3%-26.9%) of the participants had headaches before pregnancy, whereas only 17.9% (95% confidence interval, 15.9%-20.1%) had headaches during pregnancy. Although the headache prevalence was lower during than before pregnancy, it was high among the participants aged 35 years or older, those who received help in their housework, and those who were multiparous. Moreover, the Zung depression score was significantly high among those experiencing headaches. Conclusion: The significant decrease in headache prevalence observed during pregnancy may be the result of a pregnancy-specific hormonal status. However, the most significant factors influencing the frequency of headaches in the participants were related to their socioeconomic status and the severity of depression. (C) 2012 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.