SAT-128 Prospective 1-year Menstrual CycleBreast Tenderness and Swelling Experiences—data from healthy regularly cycling women initially proven normally ovulatory on two consecutive cycles

Disclosure: M. Wood: None. J.C. Prior: None. S. Shirin: None. A. Goshtasebi: None. Breast tenderness and swelling are associated with premenstrual symptoms but have not been well described in healthy, normally cycling women with known ovulatory status. There are documented negative health risks (in bone, the cardiovascular system and cancers) in association with ovulatory disturbances within normal-length cycles. Identifying breast changes across a predictable, month-apart cycle but with Subclinical Ovulatory Disturbances (SOD, short luteal phase [<10 days] and anovulation (with normal estradiol but lower or absent progesterone levels) could advance our understanding of menstrual cycle physiology, women’s health education and identification of those with chronic SOD who may benefit from cyclic progesterone therapy. Our objective was to determine whether within-woman breast tenderness and swelling experiences differed between normally ovulatory and ovulatory-disturbed cycles. In this 1-year prospective observational study, we examined daily breast tenderness (0-4) and swelling (1-5 change from usual = 3) experiences recorded via the Menstrual Cycle Diary© over ≥8 cycles (mean=13/woman) in 53 women. Ovulatory status was documented by the twice-validated Quantitative Basal Temperature© (QBT©) analysis. Cycle and ovulatory data were previously reported (Prior NEJM, 1990); Diary data were unreported. Participants were healthy, community-dwelling women, mean age 34 (32.4:35.5 years), BMI 22.0, primarily White, and about two-thirds were runners (for health or were marathon-training). Comparison of breast parameters in all normally ovulatory (n = 495) vs all SOD cycles (n = 199) (mean cycle length 28.1 [27.5-28.8 days]), showed significantly higher Breast Tenderness Score [intensity X days; 6.0 (range 1.0, 14.0) vs. 3.0 (0.0, 11.0) (P = .001)] and increased breast size [4.0 (2.0, 4.0) vs. 4.0 (0.0, 4.0) (P = .034]) in normally ovulatory cycles. However, in within-woman analysis (n = 47 women with both normally ovulatory and SOD cycles), breast tenderness/swelling did not significantly differ by ovulatory status. We plotted all ovulatory cycles (n=676) centred on ovulation; this revealed parallel timing of increases in breast tenderness and swelling in the late luteal phase. These 1-year prospective data documented that mild breast tenderness and swelling occurred before flow in cycles with normal ovulation; symptoms were less in SOD cycles. Breast changes were totally absent during the follicular phases. Presentation: Saturday, July 12, 2025