Background: While "constitution" is a commonly used term, its abstraction is often the source of confusion and misunderstanding. It is rarely scientifically measured in modern medicine, which implies that most people are not aware of the current state of their own constitution and are thus unable to receive appropriate evidence-based nursing care. Individual constitution is an influencing factor on pregnancy symptoms based on relevant theories. Purpose: This study was designed to explore correlations between women's Chinese medical constitution before pregnancy and discomfort symptoms during the first trimester of pregnancy. Methods: A descriptive and correlational design was adopted and 235 women were recruited in their first pregnancy trimester from four hospitals in southern Taiwan. Structured questionnaires used a Demographic Data Sheet, Traditional Chinese Medical Constitutional Scale (TCMCS), and Evaluation of Uncomfortable Symptoms During the First Trimester of Pregnancy to collect data. Results: Results of this study indicated that (1) 42.55 % of participants had a "normal" constitution; 26.81% had a "mixed" constitution that was either deficient in yin-xie or yang-qi as well as tan-shi-yu-zhi; 7.23% had a tan-shi-yuzhi constitution; 5.97% had a yin-xie deficient constitution; 3.40% had a yang-qi deficient constitution; 14.04% had a mixture of any two constitutions; (2) the top three discomforts reported during the first trimester of pregnancy included fatigue, frequent urination and nausea, in descending order; (3) "frequent urination," "fatigue," "heavy vaginal discharge," "dizziness," and "mood swings" had significantly positive correlations with yin-xie deficiencies, yang-qi deficiencies, and a tan-shi-yu-zhi constitution. Swelling pain in the breasts had a significantly positive correlation with a tan-shi-yu-zhi constitution. Conclusions: This research is the first to acquire evidence-based data regarding correlations between constitution before pregnancy and uncomfortable symptoms during the first trimester for pregnant women. This can assist healthcare professionals to provide more suitable perinatal nursing care before pregnancy through integrating traditional Chinese medicine and western medicine. Such can enhance the comfort of women undergoing pregnancy and promote the health of both the fetus and mother.