ScienceContemporaryglobalhigh confidence

Missing birth-control pills can cause headaches or migraines due to lower estrogen levels, especially when pills are missed at the beginning of a new pack or before the period.

Notes on verification

Confirmed by clinical/diagnostic criteria (ICHD-3 estrogen-withdrawal headache), peer-reviewed studies (Ob & Gynecology 2000, AJOG 2005 systematic review), and consumer health sources (Mayo Clinic, Hey Jane) that converge on the same mechanism and timing details. [tier=silver indep_score=0.56 clusters=5 claim_tier=notable | framework convergence=partial on Estrogen-withdrawal headache mechanism as codified in ICHD-3 and supported by clinical trial data (upstreams: ICHD-3 (International Classification of Headache Disorders), Loder et al. 2005 AJOG systematic review, Ob & Gynecology 2000 hormone withdrawal study) — publishers independent, evidence may not be | kind=empirical eligibility=high (extractor: empirical/medium)]

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