Background <p>Pregnancy-related hormonal and biomechanical adaptations increase ligamentous laxity and joint mobility, which may persist into the postpartum period and contribute to pain and functional limitations. Although prenatal Pilates attenuates ligamentous laxity during pregnancy, its effects on early postpartum recovery remain unclear. This study aimed to investigate whether continuation of a structured prenatal Pilates program until childbirth facilitates ligamentous recovery and improves functional outcomes at six weeks postpartum.</p> Methods <p>This dual-center, parallel-group randomized controlled trial included 42 primiparous women with singleton pregnancies randomized to a prenatal Pilates group or a control group receiving standard prenatal care. Assessments were conducted at baseline (14–16 weeks of gestation), late pregnancy (32 weeks of gestation), and six weeks postpartum. Outcome measures included anterior cruciate ligament (ACL) laxity assessed using a GNRB^® arthrometer, generalized joint hypermobility (Beighton score), pelvic girdle pain–related disability (Pelvic Girdle Questionnaire), and physical activity level (daily step count). Data were analyzed using linear mixed-effects models, with mode of delivery included as a covariate.</p> Results <p>Linear mixed-effects model analyses revealed significant group × time interactions for ACL laxity at 134&#xa0;N (<i>p</i> = 0.011) and 200&#xa0;N (<i>p</i> = 0.008), as well as for Beighton scores (<i>p</i> = 0.012). Ligamentous laxity and generalized joint hypermobility remained stable during pregnancy and returned toward baseline at six weeks postpartum in the Pilates group, whereas pregnancy-related increases persisted in the control group. Significant group × time interactions were also observed for pelvic girdle pain–related disability (<i>p</i> = 0.022) and daily step count (<i>p</i> = 0.027). Pelvic girdle pain decreased more markedly in the Pilates group, while physical activity levels increased substantially compared to the control group. All findings remained statistically significant after adjustment for mode of delivery.</p> Conclusions <p>Continuation of a structured prenatal Pilates program until childbirth is associated with improved ligamentous recovery, reduced generalized joint hypermobility, lower pelvic girdle pain–related disability, and higher physical activity levels in the early postpartum period, supporting its role as a feasible pre-rehabilitative strategy during pregnancy.</p> Trial registration <p>ClinicalTrials.gov Identifier: NCT07344857 (<a href="https://clinicaltrials.gov/study/NCT07344857">https://clinicaltrials.gov/study/NCT07344857</a>).Registration Date:01/08/2026.</p>