Merki–Feld GS, et al. – Researchers carried out this study to recognize the optimal interval for use of preventive migraine agents in combined hormonal contraceptives (CHC) users with estrogen withdrawal migraines (EWH), also identify in addition to migraine days in the pill–free interval, the relationship between migraine onset and day of last pill intake on one hand and the first day of bleeding on the other hand. In CHC users menstrually related migraine (MRM) mostly started on bleeding days -1 to day 4, what differed from findings in the natural cycle. Migraine started mostly on days 1–5 referring to the hormone–free interval (HFI) interval. As per this study, it appeared to be reasonable to initiate short–term prevention at the last day of pill use or the first day of the HFI and continue for 5 days.

• The researchers collected data from daily conducted headache diaries of CHC users with MRM in at least two of three cycles, visiting their clinic from 2009 to 2015 for this observational diary-based pilot study.
• For this study, they examined frequency of migraines for each hormone free day, onset of migraine, onset of bleeding and the relation of migraine to onset of bleeding in the 7-day period following estrogen withdrawal.
• Also, they identified in addition the onset of migraine attacks lasting more than 1 day (episodes).

• The inclusion criteria was met by 40 patient charts, what allowed us to investigate 103 cycles.
• In the HFI, the mean number of migraine days was 2.2 ± 1.6.
• Migraine started typically on days 1-5 and bleeding on days 3-5.
• Migraines started on days -1 to 4 in relation to the first day of bleeding.
• Despite the use of rescue medication, about half of the migraine attacks lasted longer than 24 h.