The Tokophobia Severity Scale (TSS): measurement model, power and sample size considerations

Area of Science:

• Perinatal mental health
• Psychometrics
• Clinical psychology

Background:

• Fear of childbirth (FoC) and tokophobia are growing concerns in perinatal mental health.
• Existing FoC measures have limitations in consistency, scoring, and clinical application.
• The Tokophobia Severity Scale (TSS) was developed to address these limitations.

Purpose of the Study:

• To examine the measurement model of the Tokophobia Severity Scale (TSS).
• To assess statistical power and sample size adequacy in the original TSS development study.

Main Methods:

• Replication of principal components analysis (PCA) from the original study.
• Parallel analysis (PA) and exploratory factor analysis (EFA) were employed.
• Power analysis and sample size calculations were performed using reconstructed data.

Main Results:

• A three-factor model demonstrated a significantly better fit than a unidimensional model.
• The original study was found to be underpowered based on power analysis.
• The TSS's assumption of unidimensionality may not be supported by the data.

Conclusions:

• The TSS is a potentially valuable tool for assessing tokophobia.
• The measurement model's assumptions may be based on inadequate sample size.
• Recommendations for sufficient sample sizes for future studies were provided.