Temporal trends in trunk flexor endurance and intra-abdominal pressure in postpartum women

Objectives: To describe change in trunk flexor endurance and intra-abdominal pressure (IAP)
associated with trunk flexor assessment and explore factors associated with change in trunk flexor
endurance during the first postpartum year.

Design: Ancillary analysis of an ongoing prospective cohort study.
Methods: Participants (N = 282) were primiparous women delivered vaginally. They completed trunk
flexor endurance testing while assessing IAP, body habitus measures (body mass index, waist circumference, and body composition), and questionnaires 5–10 weeks and 11–15 months postpartum. We investigated change in trunk flexor endurance by quartile of improvement and factors associated with improvement (Q4 vs. Q1-Q3) using multivariable models, adjusted for baseline endurance.

Results: Mean age was 28 ± 5 years. The median (IQR) trunk flexor hold time increased from early
to late postpartum (129/IQR = 68, 217 vs 148/IQR = 80, 265 seconds, p = .01) and mean (SD) IAP
decreased (55/SD = 13 vs 48/SD = 14 cmH20, p < .0001). The most improved group (Q4) increased
endurance time by 176 seconds (95% CI = 103, 254), were less likely to be Hispanic, more likely to
be older, more educated, and have lower measures of body habitus than women in Q1-Q3.

Conclusion: Trunk flexor endurance increased and IAP decreased over one year postpartum.
Lower body habitus and higher age early postpartum predicted greatest improvement in trunk
flexor endurance at 1 year.