Background: It is well documented that heightened levels of parenting stress have a negative influence on children's socio-emotional and behavioral development. Parenting stress may therefore be regarded as an outcome variable in its own right. This study investigated whether a sensitizing intervention influences stress reported by parents of prematurely born children until the children were age nine.
Methods: Preterm infants (N = 146, birth weight <2,000 g) were randomized to intervention (N = 72) with the Mother-Infant Transaction Program (MITP) or a preterm control group (N = 74) that received standard hospital care. A term reference group comprised 75 healthy, full-term neonates. Parents reported on the Parenting Stress Index (PSI) when the children were 6 months, 1, 2, 3, 5, 7 years old and on the PSI-Short Form (PSI-SF) at age 9. Main outcomes were the mother's and father's reports of total, child and parent-related stress. Cross-sectional and longitudinal analyses were performed using linear mixed models (LMM), taking dependency in the data caused by twin pairs and repeated measures into account. Response rates were high across all follow-ups, and still reached 85% from mothers and 72% from fathers at 9 years.
Results: Mothers in the intervention group reported better longitudinal development of child-related stress than mothers of preterm controls, as they perceived their children as being more adaptable and less moody throughout childhood until the age of seven. Less stress in the intervention group was revealed by cross-sectional analysis of maternal reports at all ages, while fathers reported similar differences at ages three and five. Parents in the intervention group reported stronger agreement on several stress scores on several occasions. Fathers with high interventional participation (mean 54%) reported significantly less stress at age nine than those who participated less. Both parents in the intervention group reported levels of stress similar to those experienced by the term reference group at all follow-ups, while differences between the preterm control and term reference groups increased.
Conclusions: This early intervention reduces stress among parents of prematurely born children to a level reported by parents of term-born children and enhances agreement between parents.
Trial registration: Clinical Trials Gov identifier NCT00222456, 05.09.2005.