The coherence of parents’ narratives about their children, which is the extent to which descriptions are accepting, consistent and complex, are thought to reflect optimal information processing of interpersonal relations and as such facilitate sensitive and responsive parenting. However, despite recent meta-analytic findings that have demonstrated links between the nature of prenatal thoughts and feelings about the unborn infant and later parenting, studies have yet to examine the narrative coherence of expectant parents’ descriptions of their infant and future parent-child relationship. This study reports on the novel use of the five-minute speech sample to capture variation in the coherence of 400 first-time expectant parents’ narratives describing their unborn infant and future relationship with them. On average, both expectant mothers and fathers struggled to provide a coherent description of their unborn infant. Coherence ratings did not show within-couple associations and were not related to either demographic characteristics, depressive symptoms or mode of conception (e.g., use of assisted reproductive technologies). An actor-partner interdependence model (APIM) did however demonstrate that reduced couple relationship quality and life satisfaction were associated with lower levels of narrative coherence in fathers, but not mothers. Model constraints illustrated the coherence of expectant fathers’ narratives about their infant and future parent-child relationship may be particularly vulnerable to the influence of the couple relationship. Future longitudinal work is needed to establish the direction of this effect, to explore the stability of narrative coherence across the transition to parenthood and to study links with postnatal parent-child interaction quality and child outcomes.