The frequency of psychotic-like experiences (PLEs) amongst new mothers is beginning to be explored but the mechanisms underlying such experiences are yet to be understood. First time mothers (N = 10,000) receiving maternity care via the UK National Health Service were contacted postnatally via Emma's Diary, an online resource for mothers. Measures assessed birth experience, trauma appraisals, post-traumatic stress symptoms, adjustment to motherhood, self-concept clarity and PLEs (in the form of hallucinations and delusions). There was a 13.9% response rate (N = 1393) and 1303 participants reported experiencing at least one PLE (93.5%). Three competing nested path models were analysed.

A more negative birth experience directly predicted delusions, but not hallucinations. Trauma appraisals and poorer adjustment to motherhood indirectly predicted PLEs, via disturbed self-concept clarity. Post-traumatic stress symptoms directly predicted the occurrence of all PLEs.

PLEs in first time mothers may be more common than previously thought. A key new understanding is that where new mothers have experienced birth as traumatic and are struggling with adjustment to their new role, this can link to disturbances in a coherent sense of self (self-concept clarity) and be an important predictor of PLEs. Understanding the development of PLEs in new mothers may be helpful in postnatal care, as would public health interventions aimed at reducing the sense of abnormality or stigma surrounding such experiences.