Good reliability and validity for a new utility instrument measuring the birth experience, the Labor and Delivery Index

To validate the Labor and Delivery Index (LADY-X), a new delivery-specific utility measure. 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. 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. 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