Gait biomechanics change during pregnancy and postpartum measured using markerless motion capture

Sixty-five percent of pregnant women experience lower extremity musculoskeletal pain and 27 % fall during pregnancy. The risks of pain and falls during pregnancy may be elevated by compensatory gait biomechanics that result from hormonal and musculoskeletal changes like weight gain and postural adjustment. Using markerless motion capture to quantify these unique biomechanics will expand our understanding of the musculoskeletal changes that occur throughout pregnancy and help clinicians manage such risks. We measured gait biomechanics in 46 pregnant patients during early pregnancy (12 weeks), late pregnancy (36 weeks), and postpartum using the markerless system as well as in non-pregnant controls. The markerless system demonstrated moderate-good inter-session repeatability in a non-pregnant cohort and moderate-excellent intra-session repeatability in non-pregnant and late pregnancy cohorts. The markerless system also demonstrated strong agreement to a marker-based system at the hip, knee, and ankle in 10 participants in late pregnancy. We compared gait kinematics, kinetics, and spatiotemporal parameters between 12 and 36 weeks of pregnancy (n = 40) and between 12-week and postpartum sessions (n = 40). Hip flexion, swing-phase knee flexion, ankle dorsiflexion and plantarflexion, and step width increased, while hip adduction, and stance-phase knee flexion decreased from 12 weeks to both 36 weeks and postpartum. Pelvis anterior tilt increased at 36 weeks but recovered postpartum. Knee extension moment decreased, and ankle plantarflexion and hip abduction moment increased at 36 weeks and recovered postpartum. These biomechanical alterations may reflect the influence of postural adjustment, weight gain, ligament laxity, or compensatory maneuvers to increase safety and comfort.