Problem: While comprehensive psychosocial assessment is recommended as part of routine maternity care, unless women engage and disclose, psychosocial risk will not be identified or referred in a timely manner. We need to better understand and where possible overcome the barriers to disclosure if we are to reduce mental health morbidity and complex psychosocial adversity. Aims: To assess pregnant women's attitude to, and reasons for non-disclosure at, comprehensive psychosocial assessment with their midwife. Methods: Data from 1796 pregnant women were analysed using a mixed method approach. After ascertaining women's comfort with, attitude to, and non-disclosure at psychosocial screening, thematic analysis was used to understand the reasons underpinning non-disclosure. Findings: 99% of participants were comfortable with the assessment, however 11.1% (N = 193) reported some level of nondisclosure. Key themes for non-disclosure included (1) Normalising and negative self-perception, (2) Fear of negative perceptions from others, (3) Lack of trust of midwife, (4) Differing expectation of appointment and (5) Mode of assessment and time issues. Discussion: Factors associated with high comfort and disclosure levels in this sample include an experienced and skilled midwifery workforce at the study site and a relatively advantaged and mental health literate sample. Proper implementation of psychosocial assessment policy; setting clear expectations for women and, for more vulnerable women, extending assessment time, modifying mode of assessment, and offering continuity of midwifery care will help build rapport, improve disclosure, and increase the chance of early identification and intervention. Conclusions: This study informs approaches to improving comprehensive psychosocial assessment in the maternity setting.