The Effect of Added Weight on Foot Anthropometry in Pregnant Women and Nulligravida Women

Abstract Background Foot anthropometry is altered by pregnancy. It is unknown if these changes are due to increased bodyweight and/or hormonal concentrations. The purpose of our study was to examine the effect of added weight on foot anthropometry in pregnancy. Methods Fifteen primigravid women and 13 nulliparous controls participated. Controls were matched to pregnant women based on self-reported pre-pregnancy weight. After informed consent, data were collected on pregnant participants in each trimester and post-partum. Foot length, width, arch index, arch height index, arch rigidity index, and arch drop were assessed. Subsequently, pregnant participants in their first two trimesters donned a weighted pack such that total weight difference from pre-pregnancy weight was 124N. Foot measurements were repeated. Third trimester participants were only measured without a pack as they were at full-pregnancy weight. In post-partum, bodyweight plus pack-weight equaled third trimester weight. For control participants, bodyweight plus pack-weight equaled third trimester weight of the pregnant participant to whom they were matched. A MANOVA was performed with the independent variables of trimester, weight condition, and leg. Tukey post-hoc analyses were performed when appropriate (α=0.05). Results Arch drop increased by 18% (p=0.007) and arch rigidity index decreased by 1% (p=0.001) while weighted across both pregnant and control groups. Increase in foot length and width and decrease in arch height index with added weight was only greater in pregnant participants compared to the control participants (p<0.05). Conclusions Adding weight produced changes in arch drop and arch rigidity index. Weight plus pregnancy was related to further alterations in anthropometry. Increased pregnancy hormone concentrations likely affect foot anthropometry in primigravid women.