Oral contraceptives and increased headache prevalence: the Head-HUNT Study.

OBJECTIVE: To examine the prevalence of headache and migraine among women using oral contraceptives (OCs) in a large, cross-sectional population-based study. METHODS: In the Nord-Trøndelag Health Study in Norway 1995-1997 (HUNT 2), 27,700 (60%) out of 46,506 invited women responded to headache questions (Head-HUNT). Among 14,353 premenopausal women, 13,944 (97%) responded to questions regarding use of contraceptives. RESULTS: There was a significant association between headache and reported use of estrogen-containing OCs in premenopausal women, both for migraine (OR = 1.4, 95% CI = 1.2 to 1.7) and for non-migrainous headache (OR = 1.2, 95% CI = 1.0 to 1.4). A significant dose relationship between headache and the amount of estrogen in the OCs could not be demonstrated. No significant association between headache and OCs containing only gestagen was found. CONCLUSION: Headache, especially migraine, was more likely among premenopausal women using oral contraceptives containing estrogen.