A comparison of sitting posture adaptations of pregnant and non-pregnant females

The postural differences between seated pregnant and non-pregnant subjects were studied, and the effects of various sitting workstation designs were assessed. Five pregnant and five non-pregnant subjects participated in this study. The experimental variables were the table-chair-vertical-distance (35 cm and 30 cm) and the seat-inclination-angle (0 degrees, + 10 degrees and + 20 degrees). The seated working postures of the last 10 min of a 50-min sitting session were videotaped and analyzed using a 2D motion analysis system. Postural differences were observed between the pregnant and non-pregnant groups which may be attributed to the changes and/or mechanisms associated with pregnancy. The increased size of the abdomen requires more room in front of the body; in the pregnant subjects this was obtained by holding the upper-arm further from the body, inclining the upper trunk more anterior, and extending the hip more. A seat with a sloping angle of 10 degrees was found to reduce the biomechanical loading on the lower back and in subjective ratings from both groups, was preferred over the other seat angles.