Impact of the Menstrual Cycle Phase on Postoperative Pain in Reproductive-Age Women Undergoing Laparoscopic Surgery

Abstract Objective To investigate the association between menstrual cycle phase and postoperative pain in reproductive-age women undergoing laparoscopic surgery, and to explore potential hormonal mechanisms. Methods This retrospective cohort study enrolled 232 reproductive-age women who underwent elective laparoscopic surgery. Patients were classified into follicular (D1–D13, n = 81), periovulatory (D14–D16, n = 52), and luteal (D17–D28, n = 99) phases according to the last menstrual period, assuming a standard 28-day cycle. The primary outcome was the 24-hour movement visual analogue scale (VAS) score. Secondary outcomes included resting and movement VAS at 24 and 48 hours, moderate-to-severe pain (VAS ≥ 4) incidence, rescue analgesic use, postoperative nausea and vomiting (PONV), and a composite endpoint. Hierarchical multivariable linear and logistic regression models were constructed. Restricted cubic splines (RCS), linear mixed-effects models, and hormone–pain correlation analyses were performed. Results Baseline characteristics were balanced across groups (all P > 0.05) except for surgical department distribution ( P = 0.005), which was adjusted for in multivariable models. In the fully adjusted model, the primary outcome did not reach statistical significance for the luteal versus follicular comparison (β = 0.218, P = 0.156). However, 48-h movement VAS (β = 0.244, P = 0.020) and 48-h resting VAS (β = 0.264, P = 0.011) remained significantly higher in the luteal phase. The adjusted odds ratio for moderate-to-severe pain was 2.27 ( P = 0.016). Luteal-phase PONV risk (OR = 3.15, P = 0.002) and composite endpoint risk (OR = 3.51, P = 0.001) were also significantly elevated. RCS analysis revealed a near-linear ascending trend of VAS with advancing cycle day (nonlinearity P > 0.4). Progesterone correlated positively with movement VAS (Spearman rho = 0.240, P < 0.001), while the estradiol-to-progesterone ratio correlated inversely (rho = − 0.223, P = 0.001). Subgroup and sensitivity analyses confirmed the robustness of findings. Conclusions The luteal phase was associated with significantly higher 48-h postoperative pain and a two- to threefold increased risk of moderate-to-severe pain and PONV compared with the follicular phase. The primary 24-h outcome did not reach significance after full adjustment. These findings indicate that menstrual cycle phase may inform perioperative pain management, warranting prospective confirmation.