Physical Activity as a Protective Factor in the Longitudinal Trajectory of Perinatal Musculoskeletal Pain: A Moderated Mediation Study

Musculoskeletal pain is a common complaint during pregnancy and can persist into the postpartum period, negatively impacting maternal quality of life. While physical activity has demonstrated preventive benefits in various clinical settings, its specific role in the evolution of perinatal musculoskeletal pain remains unclear. The aim of this study was to examine whether daily time spent exercising moderates the trajectory of musculoskeletal pain from pregnancy to the postpartum period, considering pain experienced during the first 48 h after delivery as a potential mediating variable. Methods: A longitudinal study was conducted with a sample of 117 women assessed at three time points: during the third trimester of pregnancy, 48 h postpartum, and three months postpartum. A model of moderate mediation was tested using PROCESS Macro (Model 7) for SPSS. Pain in the third trimester was specified as a predictor (X), pain at 48 h postpartum as a mediator (M), pain at three months postpartum as an outcome (Y), and exercise during pregnancy as a moderator (W) of the relationship between X and M. Results: pain in the third trimester significantly predicted pain at three months postpartum (p < 0.001), and this relationship was partially mediated by pain at 48 h postpartum. Physical exercise significantly moderated this pathway (p = 0.0057), and higher levels of exercise were associated with less association across time over time. The moderate mediation index was significant (95% CI 0.0093, 0.1095), highlighting physical activity as a relevant protective factor against persistent postpartum pain.