The influence of body mass on foot dimensions during pregnancy

• This study used a time-series approach to measure women’s feet during pregnancy.
• After 20 weeks of pregnancy, occurrence of pregnant women’s foot discomfort generally increased.
• During pregnancy, women’s foot size increased, whereas the height of arch decreased.
• Body mass accounted for more than 90% of the variation (R2) in foot dimensions during pregnancy.

In this study, a time-series approach was used to measure women's feet to accurately analyze changes in foot size and body mass during pregnancy. One-hundred women who were pregnant for the first time were asked to respond to questions on subjective complaints of foot discomfort listed in a questionnaire. Among these 100 women, a sample of 30 was obtained and used to measure the women's feet from the twentieth week of the gestation period until labor. The data (from 5 of the 30 women) were used to establish a prediction model for the influence of body mass on changes in foot size during pregnancy. The results indicate that the women subjectively complained that their shoes were too tight, resulting in foot discomfort. From the twentieth to the thirty-eighth week of pregnancy, the average increase in foot length, width, and back foot surface was 0.86 cm (3.6%), 0.25 cm (2.6%), and 18.36 cm2 (11.9%), respectively. The height of the arch decreased by an average of 0.52 cm (−24.2%). Body mass accounted for more than 90% of the variation (R2) in foot dimensions during pregnancy and, thus indicated satisfactory predictive ability. The prediction model developed in this study can serve as a reference for clinical applications and shoe design to prevent women from experiencing extreme discomfort in their feet during pregnancy.