Evidence on the psychometric properties of the Parental Reflective Functioning Questionnaire - prenatal version (P-PRFQ) can improve the assessment of prenatal parental reflective functioning (PRF). We analyzed the psychometric properties of the P-PRFQ Portuguese version in expectant mothers, specifically (1) factor structure and measurement invariance, (2) reliability, (3) criterion (known groups, convergent validity), and (4) predictive validity. Expectant mothers ( n=389) completed the P-PRFQ at the third pregnancy trimester, and self-reported questionnaires on sociodemographic, obstetric-fetal, mental health-related characteristics, romantic attachment, and depressive and anxiety symptoms. A subsample also completed self-reported measures of PRF and mother-infant bonding difficulties in the postpartum ( n=163). Results supported a three-factor model: opacity of mental states, reflecting on the fetus-child mental states, and dynamic nature of the mental states. Measurement invariance was found across sociodemographic and obstetric characteristics. Cronbach’s alpha and McDonald’s omega for the P-PRFQ total score were .63. Known-group validity was established according to sociodemographic, obstetric, and mental health-related characteristics. Convergent validity was found with romantic attachment-related anxiety, depressive and anxiety symptoms, and potentially traumatic lifetime events. Predictive validity was found with mother-infant bonding difficulties and PRF at 2 months postpartum. P-PRFQ can be a useful measure to identify PRF difficulties in perinatal care settings.