Changes in Foot Biomechanics During Pregnancy: Associations With Plantar Pressure, Low Back Pain and Daily Function...

Longitudinal data on pregnancy-related changes in plantar loading and balance are limited, particularly among Asian populations. This study investigated trimester-specific alterations in plantar pressure, static and dynamic balance, and pain-related functional interference in pregnant Taiwanese women.

Eighty-eight pregnant women were prospectively assessed across six gestational time points (8-36 weeks). Plantar pressure distribution and static balance were measured using a pressure plate system (FOOTPLATEC), and dynamic balance was evaluated using the timed up and go (TUG) test. Pain severity and its interference with daily activities were recorded using the Brief Pain Inventory. Foot oedema was assessed using a standardised grading system to evaluate trimester-specific changes. Repeated-measures ANOVA and Pearson correlation analyses were conducted.

Dynamic balance significantly declined across pregnancy, with TUG time increasing from 6.67 ± 1.11 s at 8-12 weeks to 7.24 ± 1.41 s at 33-36 weeks (p < 0.01, η² = 0.11). Medial midfoot pressure increased by 19% (from 102.56 ± 22.24 to 122.08 ± 29.93 kPa; p < 0.01). Mid-pregnancy foot pain was inversely correlated with hallux (r = -0.17) and lesser toe pressures (r = -0.18; both p < 0.05), whereas heel pressure in late pregnancy was positively associated with low back pain (r = 0.23, p < 0.05). TUG performance was consistently correlated with interference in daily activities throughout gestation (r = 0.20-0.26, p < 0.05).

Progressive redistribution of plantar loading and subtle balance changes were observed across gestation, which may contribute to discomfort and reduced mobility in some pregnant women. These findings support the importance of trimester-specific biomechanical monitoring in prenatal care.