Development and Testing of the Preparation for Labor and Birth Instrument

To develop and assess the reliability and validity of a new instrument used during the third trimester of pregnancy to measure women's confidence in their ability to achieve physiologic birth, the Preparation for Labor and Birth (P-LAB) instrument.

Two-phase instrument development study that consisted of item generation and a prospective field test.

Field testing occurred in five midwestern U.S. prenatal clinics.

Participants in the field test were 203 nulliparous and parous pregnant women who intended to give birth vaginally.

Psychometric testing consisted of test-retest reliability testing and assessments of content validity, face validity, and construct validity. We measured construct validity using exploratory factor analysis and correlation with the Sense of Coherence Scale.

The 22-item P-LAB showed good content validity, good internal consistency, and stability over time. All items had content validity index scores greater than or equal to 0.8, and the total instrument content validity index was 0.95. We identified four factors related to women's confidence in their ability to achieve physiologic birth: Planned Use of Pain Medication, Relationship With Care Provider and Supportive Birth Environment, Beliefs About Labor, and Labor Support (social and professional). Cronbach's alpha coefficient for the four extracted factors were .93, .76, .73 and .74, respectively. Intraclass correlation [95% confidence interval] for the total questionnaire was .92 [.88, .94]. We found no linear association between total P-LAB scores and sense of coherence.

Our findings demonstrate acceptable initial psychometric properties for the P-LAB instrument. Additional testing is required to evaluate the instrument's construct, convergent, and divergent validity.