Yarrow (Achillea millefolium) has a long history of use in traditional herbal medicine for supporting the female reproductive system. Historically, yarrow has been used by various cultures for its purported ability to regulate menstrual cycles, ease menstrual cramps (dysmenorrhea), and reduce excessive menstrual bleeding (menorrhagia). Traditional herbalists have often recommended yarrow as an "emmenagogue," meaning it is believed to stimulate menstrual flow. The plant has also been used as a general uterine tonic and for relieving symptoms associated with menopause.

Despite its widespread traditional use, scientific validation for these effects is limited. Some laboratory studies have identified anti-inflammatory, antispasmodic, and astringent properties in yarrow, which could provide a basis for its traditional use in easing menstrual cramps and controlling bleeding. However, robust clinical trials in humans investigating yarrow’s effects specifically on the female reproductive system are largely lacking. Most available evidence is anecdotal or based on historical use, rather than modern scientific studies.

In summary, the use of yarrow to support the female reproductive system is primarily justified by traditional knowledge and usage, rather than strong scientific evidence. Its proposed benefits are plausible based on its phytochemical profile, but more rigorous research is needed to confirm its efficacy and safety for these indications.