The purpose of this study was to explore correlations among constitution, stress, and discomfort symptoms during the first trimester of pregnancy. We adopted a descriptive and correlational research design and collected data from 261 pregnant women during their first trimester in southern Taiwan using structured questionnaires. Results showed that (1) stress was significantly and positively correlated with Yang-Xu, Yin-Xu, and Tan-Shi-Yu-Zhi constitutions, respectively; (2) Yin-Xu and Tan-Shi-Yu-Zhi constitutions had significant correlations with all symptoms of discomfort, while Yang-Xu had significant correlations with all symptoms of discomfort except for "running nose"; (3) Tan-Shi-Yu-Zhi constitution and stress were two indicators for "fatigue"; Tan-Shi-Yu-Zhi was the indicator for "nausea"; Yang-Xu and Yin-Xu were indicators for "frequent urination." Our findings also indicate that stress level affects constitutional changes and that stress and constitutional change affect the incidence of discomfort. This research can help healthcare professionals observe these discomforts and provide individualized care for pregnant women, to nurture pregnant women into neutral-type constitution, minimize their levels of discomfort, and promote the health of the fetus and the mother.