Anterior limit of stability during and after pregnancy

Pregnancy-related anatomical and physiological changes may influence postural control. However, evidence regarding limits of stability (LoS) during pregnancy and postpartum remains scarce and inconsistent.

To evaluate the effects of visual deprivation and pregnancy/postpartum stage on anterior LoS variables in healthy women and to examine whether changes in stance width are associated with changes in LoS.

Thirty healthy women were assessed during early and late pregnancy, and at two and six months postpartum. Anterior LoS was evaluated on a force plate under eyes-open and eyes-closed conditions. Center of pressure variables included postural adjustment, maximal forward lean, stable forward lean and sway parameters during maintaining maximal forward leaning: sway range in anterior-posterior and medial-lateral directions, root mean square, mean velocity, and mean frequency. Stance width was also recorded.

No interaction between visual condition and assessment time was observed. Compared with eyes open, the eyes-closed condition reduced maximal and stable forward lean and increased postural sway. Maximal and stable forward lean increased from two months to six months postpartum, whereas mean frequency decreased from early to late pregnancy. Increased stance width from early to late pregnancy was moderately associated with greater postural adjustment. Reduced stance width from late pregnancy to six months postpartum was associated with increased maximal forward lean, as well as root mean square and anterior-posterior range.

Visual deprivation significantly affected anterior LoS variables. Anterior LoS was maintained across pregnancy; however, sway frequency decreased as pregnancy progressed. The magnitude of forward lean was lower at two than at six months postpartum. Stance width was greatest in late pregnancy.