The possibility of posttraumatic growth in the aftermath of pregnancy loss has received limited attention to date. This study investigated posttraumatic growth in mothers following stillbirth compared to early miscarriage. It was hypothesised that mothers following stillbirth will demonstrate more posttraumatic growth, challenge to assumptive beliefs, and disclosure than mothers following early miscarriage. The study also sought to understand how theoretically-derived variables of the Model of Growth in Grief (challenge to assumptive beliefs and disclosure) explained unique variance in posttraumatic growth when key factors were controlled for. One-hundred and twenty women who had experienced a stillbirth (N = 57) or early miscarriage (N = 63) within the last two to six years completed validated questionnaires in an online survey relating to posttraumatic growth and key variables relevant to emotional adjustment post-bereavement. Participants who had experienced a stillbirth demonstrated significantly higher levels of posttraumatic growth, posttraumatic stress symptoms, perinatal grief, disclosure, challenge to assumptive beliefs and rumination than participants who had experienced an early miscarriage (Cohen’s d ranged .38-.94). In a hierarchical stepwise regression analysis, challenge to assumptive beliefs alone predicted 17.5% of the variance in posttraumatic growth. Intrusive and deliberate rumination predicted an additional 5.5% of variance, with urge to talk, reluctance to talk, and actual self-disclosure predicting a further 15.3%. A final model including these variables explained 47.9% of the variance in posttraumatic growth. Interventions targeting challenge to assumptive beliefs, disclosure, and rumination are likely to be clinically useful to promote psychological adjustment in mothers who have experienced stillbirth and early miscarriage.