The aim of the study was to identify whether perceived stress and significant life changes are related with partnership relation quality in mothers of preterm-born children. The study group consisted of 260 women, who gave a preterm birth. In most cases the delivery took place in the 34–36th week of pregnancy. The research consisted of two phases. Phase 1 was carried out in the Department of Obstetrics at the Medical University of Gdansk in the neonatal period (2–3 days after birth). Phase 2 was carried out in the place of residence of the mother and child during early childhood (24–30th month of the child’s life). The following research tools were used in the first phase of the research project: Analysis of nursing and medical reports, an interview questionnaire and psychological interview, The Perceived Stress Questionnaire (PSQ) (Lavenstein, the Polish version, after Plopa, 2008), The Recent Life Changes Questionnaire (RLCQ) (Rahe and Holmes, 1975), the Polish version, after Terelak 1995), and the Dyadic Adjustment Scale (DAS) (Spanier, 1976, the Polish version, after Cieślak, 1989). In the second phase of the study the respondents were once again examined using the DAS. It was shown that stress is related to partnership relationship quality and of all its components, except cohesion. The findings demonstrated that important life events are associated with a couple’s emotional expression in the neonatal period. Stressful life events do not correlate with relationship quality.