Defining trunk kinematics associated with pregnant waddling gait

A common gait pattern during pregnancy is waddling gait with increased step width, which is clinically identified by trunk sway, but the specific correlates to trunk sway remain understudied. Existing research has not kinematically validated the combination of movements as a unified waddling gait pattern. In this study we examined the relationships among trunk kinematic characteristics, step width, and balance control. Twenty-three pregnant individuals were assessed every four weeks between 18 and 34 weeks of gestation. Participants completed a quiet standing balance test and treadmill walking, from which spatiotemporal variables and trunk kinematics were calculated. Multiple linear regressions assessed whether waddling gait characteristics correlate with balance and step width. Over gestation, trunk kinematics showed no significant change. However, step width increased by nearly 1 cm through pregnancy (p = 0.044). Irrespective of pregnancy, wider step width was associated with less sagittal thorax motion with respect to global, but more thorax motion with respect to the pelvis. However, over the course of pregnancy, women who adopted more waddling gait had larger reductions in sagittal trunk motion with respect to global (R² = 0.255, p = 0.014). This study is the first to identify how trunk characteristics correlate with waddling, but only trunk sagittal motion change was specific to pregnancy change in waddling. We identified pregnancy-related gait changes to guide prescribing supportive devices or exercises for balance, back, or pelvic pain. The findings may help healthcare providers be more mindful when deciding whether to restrict or encourage trunk motion in pregnant individuals.