Pregnancy waddle validated with 3D motion capture

For the first time, researchers from the Hiroshima University, Hiroshima, Japan, have verified that the “pregnancy waddle” does exist, and their results were published early online and will appear in the July 2016 issue of the journal Applied Ergonomics.

They sought to quantify the inertial parameters of the lower trunk in eight pregnant women and seven nulliparous women, onto whom they attached 24 infrared reflective markers to the lower trunk, and used eight infrared cameras to capture standing positions. The women were then asked to perform a task that included standing up from a chair, picking up plates, and moving forward after turning to the right carrying these plates. Researchers then recorded these movements using 3D motion capture.

"Biomechanics studies like ours of how humans move are valuable for many things, like making our built environments safer or designing mobility skills," said Koichi Shinkoda, PhD, professor, graduate school of biomedical and health sciences, Hiroshima University, Hiroshima, Japan.

During pregnancy, falls have been shown to cause between 10% to 25% of trauma injuries, and the risk of falling in pregnant women can be as high as in women who are 70 years old. This type of modeling is hoped to help researchers determine better physical postures for women during—and even post-pregnancy—that they can incorporate into their daily lives to remain safe and reduce their risk of injury.

"Prior to our study, there were almost no theory-supported models of the movement of pregnant women. This model is just the start of our goal of contributing to a safe and comfortable life before and after childbirth for pregnant women," said Yasuyo Sunaga, a doctoral student in Dr. Shinkoda's lab and first author of the study.

Drs. Shinkoda and Sunaga and colleagues found that even in their first trimester, the center of mass in a pregnant women is farther forward, and to compensate, pregnant women lean backwards slightly while standing and bend their hips less when walking. Researchers concluded that such compensations may put pregnant women at greater risk for tripping over their toes and losing their balance.

"We want to find the ideal way for new mothers to carry their baby, what exercises are most effective to return to non-pregnant fitness, and what physical postures are best for work in the home or office. Now that we have the appropriate data, we hope to apply our model and make it possible to problem-solve these concerns of daily life," concluded Dr. Sunaga.

This study was supported in part by Grants-in-Aid for Scientific Research awarded by the Japan Society for the Promotion of Science (Grant Number 24792502 and 15K11664).