Fig. 3

Legend, approximated cumulative lifetime instability: On average in the US, women reach menarche (start having ovulatory menstrual cycles) at age 14, and enter menopause (cease having ovulatory menstrual cycles) at age 49. Individual ages can vary widely. The luteal phase when relaxin peaks, CD21 to CD24, is consistent among women. With an average of 13 menstrual cycles per year and 4 days of instability per cycle, over 35 years of menstrual activity, women are subject to roughly 5 years of TMC joint instability before reaching age 50