Development and Testing of the Comprehensive Prenatal Care Index: Relationship With Preterm Birth and Small for Gestational Age Across Racial and Ethnic Groups

Introduction: Preterm birth and small for gestational age (SGA) are significant public health concerns in the United States, with pronounced disparities across racial and ethnic groups. Traditional prenatal care adequacy indices have limitations in fully capturing their multifaceted nature. Our study introduces the Comprehensive Prenatal Care Index (CPCI) to provide a more holistic assessment of prenatal care by integrating key elements of prenatal counseling and health promotion. Methods: This cross-sectional study used the Pregnancy Risk Assessment Monitoring System 2016-2021 data. The CPCI was developed based on a comprehensive literature review, incorporating components such as timing, frequency, and content of prenatal visits. The index was validated using Item Response Theory (IRT) and compared with the Kotelchuck and Kessner Indices. Results: The study included 139,181 pregnant women. The CPCI demonstrated strong internal consistency (Cronbach's α, 0.75; ω total, 0.81). IRT analysis confirmed the index's ability to capture variability in the quality of prenatal care, with item difficulty parameters ranging from −2.93 to +2.10. CPCI scores were significantly associated with reduced odds of adverse birth outcomes. Adequate CPCI care was linked to a 63% reduction in the odds of preterm birth among non-Hispanic White women, with similar reductions observed in Hispanic women (odds ratio [OR], 0.59) and Asian women (OR, 0.38). For SGA, adequate care was protective among non-Hispanic White (OR, 0.86) and Hispanic women (OR, 0.82) but showed mixed results in other groups. Discussion: The CPCI provides a more inclusive measure of the quality of prenatal care compared with traditional indices. The study's findings suggest a significant role of comprehensive prenatal care in reducing adverse birth outcomes and addressing racial and ethnic disparities. Future research should focus on refining the CPCI and exploring its applicability in diverse populations to inform targeted and culturally sensitive prenatal care strategies.