The development of triadic interactive competences during the first 18 months of baby's life.

Background: this paper presents a longitudinal study of the development of family interactions from pregnancy to the first 18 months of the infant's life. Theoretical and methodological work is based on Lausanne developmental systems approach, which focuses on the father-mother-infant primary triangle as the interactive matrix to the development of emotional relationships. The study has two main aims: a)to investigate the psychometric characteristic of the prenatal and postnatal Lausanne Trilogue Play procedure in the Italian context and the comparison with the Lausanne validation studies; b)to study the development of traidic families ' interactions in the family and the patterns of stability and/or change during the first 18 months of infants' life. Methods: 70 non-referred primiparous families were recruited at child birth courses. We used the Lausanne Trilogue Play (LTP) an observational procedure to evaluate the development of the interactive competences of families. Families played an interaction with a doll at the 7th month of the pregnancy, and then played with the infant at 4, 9 and 18 months. Results: aim 1: the data show a good inter-rater reliability of LTP coding system (a = .73) and a consistent factorial structure (KMO = .79; Bartlett test (N = 70,10) = 104.09, p=.001) in the Italian context; the results are in line with Lausanne validation studies (Carneiro et al., 2006; Favez et al., 2006). Aim 2: compared to the Lausanne longitudinal results Italian data show that the interactive competences displayed by the parental couple durign the pregnancy are predictive of family interactions after the baby's birth. In opposition with the Lausanne longitudinal results which show a relative interactions finding a linear relation between time and the family interactions (t=4.78; p = .001): there is an increase of 2,35 points in each observational phase. Conclusions: co-parental capacities in pregnancy represent an interactive matrix for the construction of the early family relationships in the first year. During the first 18 months, the development of family interactions increased in a homogenous way: this result can be considered like a common model in the development family interactions.