The effects of pelvic belt use on pelvic alignment during and after pregnancy: a prospective longitudinal cohort study

BACKGROUND: Pelvic alignment changes during pregnancy and post-childbirth. Pelvic belts exert external forces that compress and stabilize the joints, and therefore, could influence pelvic alignment. However, limited information is available regarding this potential effect. Therefore, the purpose of this study is to investigate the influence of pelvic belt use on pelvic alignment during and after pregnancy. METHODS: Data of 201 pregnant women in late pregnancy and 1 month after childbirth were used. Pelvic alignment measurements, including anterior and posterior pelvic width, pelvic asymmetry, and pelvic belt use during and after pregnancy were investigated. Participants were divided into four groups according to pelvic belt use: before and after childbirth (BAC), before childbirth only (BC), after childbirth only (AC), and non-use (NU). Then, an initial one-way ANOVA was conducted to compare the amount of change in pelvic alignment from late pregnancy to post-childbirth between the groups. After the initial analysis, a multivariate regression analysis was performed to determine the statistically significant differences between the groups to consider other factors that influenced pelvic alignment such as age, BMI, number of previous childbirths, vaginal delivery and pelvic asymmetry in late pregnancy. Next, a cutoff point for subgroup stratification based on the weekly duration of pelvic belt use and inter-group changes in pelvic alignment were compared. RESULTS: As the result of the initial one-way ANOVA, the decrease in pelvic asymmetry from during pregnancy to postpartum for BAC was greater than that for AC. Moreover, multiple regression analysis showed that the effect of pelvic belt that was revealed in the initial analysis was statistical significance even after adjustment for other factors. Moreover, pelvic asymmetry in the BAC group decreased, compared to being increased or unchanged in the NU and AC groups when the group cutoff time was 7 h per week. CONCLUSIONS: Continuous and extended use of pelvic belts during and after pregnancy might be related to modifications of pelvic asymmetry in the perinatal period. Therefore, the instruction of correct and comfortable usage and the recommendation of continuous use of pelvic belt especially during pregnancy are required for prevention of some discomforts related to pelvic malalignment. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12884-019-2457-6) contains supplementary material, which is available to authorized users.