Trajectories and Determinants of Female Sexual Function from Pregnancy to 12 Months Postpartum: Obstetric Trauma, Sleep Quality, Depressive Symptoms, and Relationship Satisfaction

<b>Background and objectives:</b> Sexual function commonly declines during late pregnancy and early postpartum, but recovery is heterogeneous and influenced by obstetric and psychosocial factors. We aimed to (i) describe longitudinal Female Sexual Function Index (FSFI) trajectories from the first trimester to 12 months postpartum and (ii) test whether sleep quality and relationship satisfaction are independently associated with sexual function at 6-12 months postpartum, beyond obstetric factors and depressive symptoms. <b>Methods:</b> In this single-center prospective cohort study, pregnant women (singleton pregnancy, ≥18 years, enrolled ≤20 gestational weeks) completed the FSFI at six timepoints: first trimester, second trimester, third trimester, 6-8 weeks postpartum, 3 months postpartum, and 6-12 months postpartum. At 6-12 months postpartum, participants also completed the Patient Health Questionnaire-9 (PHQ-9) for depressive symptoms, the Pittsburgh Sleep Quality Index (PSQI) for sleep quality, WHOQOL-BREF for quality of life, a brief body-image disturbance scale, and a 1-5 relationship satisfaction rating. Delivery was categorized as vaginal low trauma, vaginal higher trauma, or cesarean. Multivariable linear and logistic regression modeled FSFI at 6-12 months postpartum and FSFI-defined dysfunction (FSFI < 26.55). <b>Results:</b> Among 112 women, FSFI-defined dysfunction at 6-12 months postpartum affected 58.0% (65/112). Mean FSFI declined from the first trimester (26.5 ± 4.1) to 6-8 weeks postpartum (18.8 ± 4.3) and recovered by 6-12 months postpartum (25.4 ± 5.0) (time effect <i>p</i> < 0.001). Dysfunction prevalence differed by delivery group (42.2% vaginal low trauma, 63.2% cesarean, 75.9% vaginal higher trauma; <i>p</i> = 0.012). In adjusted models, worse sleep quality and higher-trauma vaginal birth increased the odds of dysfunction, whereas higher relationship satisfaction was protective. Depressive symptoms and sleep quality were independently associated with lower FSFI in linear models. <b>Conclusions:</b> Late-postpartum sexual function follows a nadir-then-recovery trajectory shaped by additive psychosocial (sleep, mood, relationship) and obstetric trauma factors, supporting multi-domain postpartum screening and targeted referral pathways.