Background:​ The postures of the trunk and of the head relative to the trunk adopted during the specific task of head load carriage were measured for a group of pregnant women and a control group of non-pregnant women because this activity was identified as a risk factor for back pain during pregnancy.

Methods:​ The postural data of the trunk and of the head relative to the trunk were collected using two inclinometer devices and an electrogoniometer, respectively.

Findings:​ During walking, the load on the head caused significantly larger upper trunk extension and smaller flexion of the head relative to the trunk. The amplitude of motion of the upper trunk and of the head relative to the trunk, as measured by the standard deviation of walking angles, was found to decrease as a result of carrying a load on the head and compensated by increased motion at the sacrum. Pregnant women showed larger upper trunk movements than their counterpart in the frontal and sagittal planes during the unloaded walking trials.

Interpretation:​ These posture modifications were believed to be adopted by the subjects to provide better stability for the load during walking. These prolonged postural strains caused by the trunk being displaced from its normal position can lead to muscle fatigue and ultimately to musculoskeletal injuries. The larger movements of the upper trunk for the pregnant women were hypothesized to be due to the enlarged abdomen of pregnant women as it creates a larger moment about L5/S1 and increases instability.