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06: Longitudinal change in pelvic floor muscle strength in parous women

      Objectives

      (1) To estimate the longitudinal change in pelvic floor muscle strength in parous women and (2) to identify maternal and obstetric characteristics associated with this change.

      Materials and Methods

      This is an IRB approved prospective cohort study of parous women. Participants were recruited 5-10 years after their first delivery and followed annually. Pelvic floor muscle strength (peak pressure with voluntary contraction) was measured at two annual visits approximately 4 years apart, using the Peritron perineometer. We calculated the change in peak pressures, standardized per 5-year interval. Linear regression was used to identify maternal and obstetrical characteristics associated with a change in peak pressure. The obstetrical variable of greatest interest was delivery group. Participants were classified into six delivery groups (considering all deliveries for each multipara). Delivery categories included three cesarean-only groups: all cesareans before labor, at least one cesarean during active labor, and at least one cesarean after complete cervical dilation. The other three groups included women who had at least one vaginal birth: spontaneous birth only, at least one vacuum-assisted vaginal birth, and at least one forceps-assisted vaginal birth. Statistical analysis was completed with STATA (StataCorp 2015, version 14 SE, College Station, TX).

      Results

      Five hundred forty-three participants completed two perineometer measurements at least 2 years apart (median 4 years [IQR 3.1-4.8]). At baseline measurement, women were, on average, 40 years old and 8 years from first delivery. There was a strong correlation between the first and second perineometry measurement (R2 = 0.7). Median 5-year change in pelvic floor muscle strength was 1.22 (IQR -5.64-9.88) cm H2O. Change in peak pressure was associated with delivery group (Figure and Table) and obesity (Table). In multivariable analysis controlling for obesity, the association between delivery group and change in pressure remained significant.

      Conclusion

      Among parous women 8 years from first birth, pelvic muscle strength increased an average of 1.22 cm H20 per 5-years; change in strength was associated with a history of cesarean versus vaginal birth and with obesity.
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