There is a paucity of information on couple relationship quality in mothers of preterm infants during the first year of life. Aim: To determine couple relationship quality in mothers of very preterm infants in comparison to mothers of term infants and to examine maternal and infant factors associated with impaired couple relationship for the preterm mothers. Methods: At 4 and 12 months (corrected for prematurity for the preterm cohort), the mothers completed the Dyadic Adjustment Scale, the Edinburgh Postnatal Depression Scale, the Parenting Stress Index and the Short Temperament Scale. At 12 months, the infants had a neurodevelopmental assessment. Results: 86 mothers of preterm infants and 97 term mothers participated at 4 months, with 101 mothers of the preterm infants and 98 term mothers participating at 12 months. Comparisons of the two groups revealed no differences in Dyadic Adjustment or for any of the subscales. For the preterm mothers at 4 months, the independent variables associated with poor dyadic adjustment were ethnicity and higher levels of parenting stress. At 12 months, parenting stress was also an independent variable associated with impaired couple relationship. Conclusions: No differences in the incidence of poor quality couple relationship was found between mothers of very preterm and term infants. For preterm mothers, impaired couple relationship was associated with parenting stress.