title: Good reliability and validity for a new utility instrument measuring the birth experience, the Labor and Delivery Index.
abstract: OBJECTIVE
  To validate the Labor and Delivery Index (LADY-X), a new delivery-specific utility measure.
  
  
  METHODS
  In a test-retest design, women were surveyed online, 6 to 8 weeks postpartum and again 1 to 2 weeks later. For reliability testing, we assessed the standard error of measurement (S.E.M.) and the intraclass correlation coefficient (ICC). For construct validity, we tested hypotheses on the association with comparison instruments (Mackey Childbirth Satisfaction Rating Scale and Wijma Delivery Experience Questionnaire), both on domain and total score levels. We assessed known-group differences using eight obstetrical indicators: method and place of birth, induction, transfer, control over pain medication, complications concerning mother and child, and experienced control.
  
  
  RESULTS
  The questionnaire was completed by 308 women, 257 (83%) completed the retest. The distribution of LADY-X scores was skewed. The reliability was good, as the ICC exceeded 0.80 and the S.E.M. was 0.76. Requirements for good construct validity were fulfilled: all hypotheses for convergent and divergent validity were confirmed, and six of eight hypotheses for known-group differences were confirmed as all differences were statistically significant (P-values: <0.001-0.023), but for two tests, difference scores did not exceed the S.E.M.
  
  
  CONCLUSIONS
  The LADY-X demonstrates good reliability and construct validity. Despite its skewed distribution, the LADY-X can discriminate between groups. With the preference weights available, the LADY-X might fulfill the need for a utility measure for cost-effectiveness studies for perinatal care interventions.
authors.affiliation: Department of Medical Decision Making, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands. Electronic address: f.r.gartner@lumc.nl.
authors.forename: Fania R
authors.initials: FR
authors.lastname: Gärtner
authors.affiliation: Department of Obstetrics & Gynaecology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Esteriek
authors.initials: E
authors.lastname: de Miranda
authors.affiliation: TNO Child Health, Schipholweg 77-89, 2316 ZL Leiden, The Netherlands.
authors.forename: Marlies E
authors.initials: ME
authors.lastname: Rijnders
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands.
authors.forename: Liv M
authors.initials: LM
authors.lastname: Freeman
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Middeldorp
authors.affiliation: Department of Obstetrics, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands.
authors.forename: Kitty W M
authors.initials: KW
authors.lastname: Bloemenkamp
authors.affiliation: Department of Medical Decision Making, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Stiggelbout
authors.affiliation: Department of Medical Decision Making, Leiden University Medical Centre, Albinusdreef 2, 230 RC Leiden, The Netherlands.
authors.forename: M Elske
authors.initials: ME
authors.lastname: van den Akker-van Marle
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000523:psychology*; D036801:Parturition / Q000523:psychology*; D011247:Pregnancy; D011594:Psychometrics / Q000295:instrumentation*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards
keywords: Labor experiences; Measurement properties; Obstetrics; Patient-reported outcome measure (PROM); Questionnaire; Utility measure