Background: The longitudinal study examines the effectiveness of a psychological support treatment for high-risk pregnancies using a between-groups design. It assesses the treatment’s impact on depression and fear of COVID-19 at three time points, and on prenatal attachment between the 20th and 24th weeks of gestation (T0), postnatal attachment 15–20 days after birth (T1), and three months after birth (T2). Additionally, the study evaluates the treatment’s effectiveness on PTSD related to childbirth and parental distress at T1 and T2. Methods: The study involved 117 parents experiencing high-risk pregnancies from a Sicilian hospital: 84 mothers (40 in the experimental group, 44 in the control group) and 33 fathers (19 in the experimental group, 14 in the control group). Results: ANOVA results showed that the psychological treatment was effective for maternal variables such as postnatal attachment and parental distress, and for paternal variables such as depression, prenatal attachment, PTSD symptoms, and parental distress (ANOVA, p < 0.05). Conclusions: The study highlights the growing evidence for providing continuous psychological support to couples with high-risk pregnancies, emphasizing that this support should extend beyond childbirth to assist families through this transition.