ObjectiveThis is the first perinatal interpersonal psychotherapy group (P-IPTG) implemented for distressed women from pregnancy to postpartum. The aim is to explore the changes in postpartum adjustment for women who receive/do not receive P-IPTG and compare the changes of the two groups. MethodsA quasi-experimental longitudinal design was applied to Taiwan community women. The sample sizes of the intervention and control groups were 25 and 233, respectively. Participants replied to measures four waves from their third trimester to one year postpartum. The intervention group participants received an eight-session P-IPTG, which consisted of four sessions in pregnancy and four in postpartum. Within-group changes were examined by repeated measure ANOVA, and between-group changes were compared by generalized estimating equations (GEE). ResultsANOVA results showed that depression decreased from baseline to four months postpartum in the intervention group (p < 0.05). In the general dyadic relationship, no change was noted in the intervention group, while there was a reduction in the control group (F = 13.52, p < 0.001, eta2 = 0.055). GEE comparison indicated favorable changes in the intervention group: greater reduction in depression at four months postpartum (β = -3.35, Wald χ2 = 6.17, p = 0.013), greater improvements in perceived partner support at four and eight months postpartum (βs = 3.18, 3.12, Wald χ2s = 4.59, 3.95, ps = 0.032, 0.047), and greater enhancement in relationship satisfaction with mothers-in-law at eight months postpartum (β = 0.59, Wald χ2 = 4.81, p = 0.028). ConclusionP-IPTG can make favorable trends of change in postpartum depression and partner/in-law relationships. This pilot study lays a foundation for further research in longitudinal perinatal interventions.