Development and Internal Validation of a Psychosocial Nomogram for Antenatal Depressive Symptoms in Third-Trimester Pregnant Women at a Regional Hospital in Southern Vietnam

Purpose: Antenatal depression is common and under-recognized, yet few individualized tools exist to support its identification in obstetric practice in low- and middle-income countries. We estimated the prevalence of a positive antenatal depression screen among third-trimester pregnant women in southern Vietnam and developed and internally validated a psychosocial nomogram for the concurrent probability of a positive screen. Patients and Methods: Within a prospective study at Long Khanh Regional General Hospital (July 2025 to May 2026), 968 women at 28 weeks of gestation or later were screened with a Vietnamese-language version of the Edinburgh Postnatal Depression Scale (EPDS; positive screen defined as a score ≥ 13). Sociodemographic, obstetric, marital, family, and social variables were recorded at the same visit, so predictors and outcome were measured concurrently (a diagnostic rather than a prognostic model). Candidate predictors with p< 0.25 in univariable logistic regression entered a multivariable model reduced by backward elimination (p< 0.05). Results: The prevalence of a positive screen was 16.5% (160/968; 95% CI 14.3– 19.0). Six variables were retained in the final model: an adverse family event (adjusted odds ratio [aOR] 5.25), marital conflict (aOR 3.64), a family history of depression (aOR 2.76), neighbourhood or workplace conflict (aOR 2.48), work-related pressure (aOR 2.22), and a lack of psychosocial support (aOR 1.77). Apparent discrimination was good (area under the curve 0.807, 95% CI 0.769– 0.847) and fell to an optimism-corrected 0.782 after bootstrapping the full procedure; the optimism-corrected calibration slope was 0.88 and calibration-in-the-large was near zero. On decision curve analysis the nomogram gave a higher net benefit than screening all women at threshold probabilities above about 10%. Conclusion: About one in six third-trimester women screened positive for depressive symptoms. A nomogram based on six readily recorded psychosocial variables showed good apparent and promising internally validated performance and may support psychosocial risk stratification where universal formal screening is difficult. Keywords: antenatal depression, Edinburgh Postnatal Depression Scale, nomogram, prediction model, pregnancy, Vietnam