Differences in Load Symmetry of the Lower Extremities in Postpartum Women During Daily Tasks and Childcare Loading Conditions

In 2021, over three and a half million women entered the postpartum period in the United States [1]. Despite their prevalence, postpartum health is a largely overlooked area. After delivery, 25% of women within this population experience lumbopelvic or pelvic pain during the typical postpartum period [3], up to 8 weeks post-delivery, and research has found these women may continue to experience pain years after delivery [4]. Persistent pelvic region pain in postpartum women may result in lower limb load asymmetry. Additionally, external loading from carrying a child may alter the degree of asymmetric loading that exists in the lower limbs. Therefore, the first purpose of this study was to investigate the effect of daily tasks on lower extremity load symmetry using metrics that have successfully identified load asymmetry in other populations. Load symmetry was found to differ between task, with the largest asymmetry occurring between limbs during the sit-to-stand task for the peak impact force (PIF = 9.08% symmetry) and during the stair descent task for the average loading rate (ALR = 15.43% symmetry). The increase in asymmetry during these tasks may be attributed to increased muscle activation and force production. The second purpose of this study was to investigate the effect of an external child load on lower extremity load asymmetry during a 14-meter level walking task. A significant increase was found between the no load and both child load conditions for PIF and ALR (p <0.001 for both metrics). No statistically significant differences in symmetry were found between carrying the child centrally in a carrier and carrying on one side of the body without a carrier. The lack of difference in asymmetry during child carrying conditions may indicate mothers naturally compensate for the external child load as both ALR and PIF values increased during these conditions, but asymmetry was not impacted. Our results indicate the need to continue to examine different carrying conditions in postpartum women to better understand risk factors for pain or injury and provide evidence-based recommendations for postpartum activity progression.