To investigate between and within-woman differences in the association between menstruation and migraine days.
Prior diary studies have shown that at the population level, aggregating across individuals, the odds of migraine increase during the perimenstrual window (from day -2 to day +3, where +1 is the first day of bleeding). These studies have been neither long nor large enough to assess the association between migraine and menses from an individual perspective. Consequently, existing research on menstrual-related migraine has largely overlooked between and within-woman variation that is critical for progressing clinical understanding and practice.
Intensive longitudinal data for the current study were collected in a digital platform (N1-Headache ) that tracks individual migraine-related factors daily. Participants for the current study were actively menstruating adult (18+ years old) women who used the platform. Two variables were of primary interest, migraine day (no/yes) and menstrual status (inside or outside the 5-day perimenstrual window).
The sample consisted of 203 women with a mean age of 35.6 (SD = 8.7) years. At baseline, the women reported an average of 30.6 (SD = 23.6) headache days over the last 3 months. Analyses were based on a total of 53,302 days (median of 150 per person), 18,520 of which were migraine days (median of 44 per person), and a total of 2,126 menstrual cycles (median of 7 per person). Results showed that the 5-day perimenstrual window was associated with a 34% increase in odds of a migraine day compared to other days (OR = 1.34, 95% CI: 1.23-1.45, p < 0.0001). Importantly, there was between and within-woman variability in the association between menses and migraine days (between-woman variability: p = 0.002; within-woman [between-cycles] variability: p < 0.0001). Exploration of these individual differences demonstrated that relationship between menses and migraine days varied more within-person across cycles than between women.
This study supports previous research and demonstrates that the odds of migraine days are elevated from day -2 to day +3 of the menstrual cycle. We also show that the effect of menses on migraine days varies more within-woman than between-women. This work provides an initial foundation for better understanding menstrual-related migraine from the perspective of the individual patient.