The utility of a nursing model as a framework to understand and explain a health phenomenon is fundamental to guide nursing practice. In this article, the authors aim to provide an examination of the Roy adaptation model as a basis for the development of an instrument used for assessing the health needs of pregnant women. With the congruence between the concepts in the Roy adaptation model and antenatal practice, an antenatal assessment instrument is developed. The assessment areas focus
on pregnant women’s behaviors in the four adaptation modes. The current experience is valuable for nurses who are involved in instrument development and midwifery practice.