The association between pregnancy, pelvic girdle pain and health-related quality of life – a comparison of two instruments

BACKGROUND: The main purposes in this cross-sectional study were to study the impact of pregnancy and pelvic girdle pain (PGP) on health related quality of life (HRQoL), by comparing the scores on different domains of two HRQoL instruments in pregnant women with population norms as well as in women with severe and less severe PGP. Further, to explore the association between PGP and HRQoL and whether the two instruments differ in the way they assess the influence of PGP on HRQoL. METHODS: Pregnant women in gestation week 30 completed questionnaires containing the Short Form Health Survey (SF-36) and the Nottingham Health Profile (NHP). Additional variables, self-reported PGP, pain location in the pelvis and response on clinical tests were also collected. HRQoL scores were compared with expected age adjusted mean scores and comparisons between groups with different severity of PGP were made, using Mann-Whitney U, t-tests and Hodges-Lehman method. RESULTS: Two hundred eighty-three pregnant women, mean age 31.3 (SD 4.2) years, participated. We found statistical significant differences in all domains of both HRQoL instruments in late pregnancy compared to the expected age-adjusted means of the reference populations (p ≤ 0.003) except for Social isolation (p = 0.775). Women with PGP had lower HRQoL than women without, and the most affected women scored lowest. SF-36 detected a deficit in Social Function compared to norms whereas the NHP showed no evidence of Social Isolation. CONCLUSIONS: Both instruments revealed changes in HRQoL in pregnant women compared with population norms. Pregnancy itself influences HRQoL and having PGP gave an additional impact. The consistency of the correlations between SF-36 and NHP domains across the sub-groups found in this study suggests convergent validity across levels of impairment. The results in social domains vary between SF-36 and NHP in pregnant women and might be due to the basic design (construction) of the tools.