ABSTRACT Objective This post-hoc analysis of data extracted from a prospective study aimed to explore for the first time if the efficacy of fremanezumab in preventing difficult-to-treat migraine, according to ICHD-III, would differ between pre-menopausal and post-menopausal women. Methods A total of 171 (aged 18–70 years) fremanezumab-treated female migraine patients for six consecutive months were classified to those at pre-menopausal (n = 82) or post-menopausal (n = 89). Monthly headache days (MHD), disability, and quality of life (QOL) outcomes were assessed at baseline and at week 24 post-fremanezumab within subgroups and were then compared between them. Safety and tolerability were also assessed. Results In both groups, fremanezumab demonstrated significant reductions in MHDs, reduced disability, and higher QOL scores at week 24 post-treatment, compared to baseline. However, the between-subgroup comparison documented that pre-menopausal women and those at post-menopausal comparably benefited with significant reductions in overall MHDs (p = 0.883). Less disability, according to MIDAS (p = 0.696) and HIT-6 scores (p = 0.912), as well as higher QOL scores at week 24 post-fremanezumab, were also comparably evident in both groups. Safety was excellent across both subgroups. Conclusion Fremanezumab can be considered a very effective treatment option for preventing migraines in difficult-to-treat women, aged 18–70 years, regardless of their menopausal status.