COMPARATIVE STUDY OF THE FOOT ARCH INDEX AMONG PREGNANT AND NON-PREGNANT WOMEN IN A SOUTH EASTERN NIGERIA COMMUNITY: A CROSS-SECTIONAL ANALYSIS

The weight bearing and distribution functions of the foot are fortified by the presence of the foot arches. The arches of the foot, especially the medial longitudinal arch add to the weight bearing capacity and resiliency of the foot (1). As pregnancy progresses, the position of the centre of gravity is altered as well as an increase in body mass which translates to an increase in the load transferred to the weight bearing joints. The resultant effects of these changes increases in relation to the distal weight bearing segments of the body, especially the foot, causing muscle imbalances, distorted integrity of the weight bearing structures and their related soft tissues. Studies have reported a posterior shift in the centre of pressure of the foot in compensation for the increased anterior abdominal mass during pregnancy (2). In addition to these physical changes, hormonal influences of relaxin and oestrogen lead to an increased ligamentous laxity, compromising joint stability (3,4), with a resultant arch collapse during pregnancy (5,6). Studies in different locations have reported changes in the foot arches, indicating an increased likelihood towards the occurrence of pes planus, in the pregnant population (3,7-11). Other studies have also shown significant increases in foot width, length, and volume with a concomitant decrease in arch height during pregnancy (12,13). However, such pregnancy-related changes and their associations with gestational trimesters have not been investigated in a Nigerian population. Obesity is an associated risk factor for pes planus (17). Previously, changes in anthropometric indices indicating obesity have been reported among Nigerian pregnant women (14-18) but their relationship with pregnancy-induced arch collapse (pes planus) have not been explored. This gap in knowledge may be contributing to the limited or lack of foot care during pregnancy and postpartum periods, among women’s health physiotherapists in Nigeria. With the aim of providing baseline information needed for enhancement of research in this green uncultultivated area of women’s health practice in Nigeria, there is need to compare the arch indexes of pregnant and nulliparous Abstract Objective: Physical and hormonal changes during pregnancy result in biomechanical alterations which result in readjustments in the musculoskeletal system. Influence of these changes on the foot during gestation has been understudied. The aim of this study was to compare the arch indexes of pregnant and non-pregnant women and then determine the relationship between arch index and each of gestational age and body mass index (BMI) of pregnant women. Materials and Methods: In this study, 328 (215 pregnant women in different trimesters and 113 nulliparous women) participants were selected from Enugu in South-Eastern Nigeria. Their arch indexes were obtained from their foot prints. Data was summarized using frequency counts, mean, standard deviation and percentages. Inferential statistics of independent t test and Pearson correlation test were used to determine the differences and relationships among variables with alpha level set at P < 0.05. Results: Results showed that a greater percentage of the pregnant women (57.2% on the right foot and 59.1% on the left foot) had low arches, indicating pes planus as compared to their age-matched nulliparous counterparts (19.5% on the right and 23.3% on the left). Statistical analysis further showed significant differences between the arch indexes of women in both groups. No significant relationship was found among gestational trimesters, BMI and arch index of pregnant women. Conclusion: Pregnant women have lower arch indexes, indicating pes planus, than nulliparous women. Gestational trimesters and BMI had no associations with the arch index during pregnancy.