Changes in posture and feet and relationship with low back pain during pregnancy among Japanese women

Abstract

Purpose

This study aimed to clarify the relationship between foot and postural changes and low back pain during pregnancy.

Methods

The study consisted of a questionnaire about low back pain during pregnancy and measurement surveys. The first survey was conducted at 14–16 weeks of gestation, the second at 24–26 weeks, and the third at 34–36 weeks. The participants were 14 pregnant women. We attached a spherical marker to the anterior superior iliac spine and posterior superior iliac spine. Using a digital camera, we photographed their standing postures from the sagittal plane and calculated the pelvic tilt angle. We applied a free curve ruler to measure the spinal curve, which was then traced on paper to calculate the thoracic kyphosis and lumbar lordosis angles. Participants were asked to adopt a natural standing posture barefoot on the flat glass plate of the pedoscope, and the state of the plantar surface touching the ground was photographed using a digital camera. The lower end of the navicular tuberosity was marked in the standing position, after which we measured the foot length and navicular height, divided the navicular height by the foot length, and multiplied by 100 to calculate the arch height. Statistical analysis was performed for each measurement item and a value of less than 5% was set as the significance level.

Results

The participants were nine primiparous women and five multiparous women, and 10 women developed low back pain during pregnancy; there was a tendency for the pelvis to tilt forward, the foot arch to flatten, and lordosis of the lumbar spine changed from decreased to increased as the pregnancy progressed, but the differences were not significant. The left ground contact plantar surface area ratio decreased significantly over time, and the ground contact area decreased as the pregnancy progressed (p<0.01). There were no significant differences over time in the pelvic tilt, thoracic kyphosis, and lumbar lordosis angles, arch height ratios, and ground contact plantar surface area ratios between those with and without low back pain during pregnancy, and between childbirth experiences.

Conclusions

Pregnant women tended to exhibit an increased pelvic tilt angle and decreased lumbar lordosis from the first to the second trimester of gestation, and increased values from the third trimester. Although the foot tended to flatten owing to the increasing load of the uterus, the ground contact area of the foot did not necessarily increase, and the toes were considered in a floating state because of the weight support by the heel. The anatomical characteristics of the uterus showed that pregnant women were more likely to bear weight on the right side during the third trimester of gestation. The onset of low back pain during pregnancy was associated with multiparous women, flattening of the foot arch, and lumbar spine alignment, which addressed the protrusion of the abdomen associated with uterine enlargement.