Background: Depression is frequently seen among pregnant women. This is called antenatal depression (AND). Aim: Our aim was to identify clusters of AND and its core symptoms. Methods: The Patient Health Questionnaire-9 (PHQ-9), Pregnancy-Unique Quantification of Emesis and Nausea (PUQE-24), and Nausea and Vomiting of Pregnancy Quality of Life Questionnaire (NVP-QOL) were distributed to 382 pregnant women with a gestational age of 10 to 13 weeks who were attending antenatal clinics. The two PHQ-9 subscale scores were entered into a 2-step cluster analysis. The PHQ-9 items' capacity to identify AND were examined in terms of the area under curve (AUC) of a receiver operating characteristic (ROC) analysis. The selected symptom items were examined for their diagnostic capability in terms of the graded response model (GRM) in the item response theory (IRT) analysis. Results: Three clusters emerged. Cluster 3 scored highly in the scores of the two PHQ-9 subscales and the two emesis scales. In the ROC, five items showed an AUC > 0.80. The GRM identified four items with high information: 'loss of interest', 'depressed mood', 'self-esteem', and 'poor concentration'. Conclusions: The core symptoms of antenatal depression were four non-somatic symptoms; particularly, 'depressed mood' and 'loss of interest'. AND did not exist alone, but was accompanied by nausea and vomiting. Hence, we propose a new category: emesis-depression complex among pregnant women.
Keywords: antenatal depression; diagnostic entity; emesis.