In a prospective, controlled trial we assessed correlations between couple structure, birth preparation and fetal outcome in 158 couples (316 individuals). 88 couples (study group, SG) attended 8 hours of birth preparation classes (BPC). 70 couples served as controls. For couple diagnostic, we used OLSON's two dimensional circumplex model with the FACES III questionnaire, which evaluates the dimensions cohesion and adaptability. In the SG "structured-connected" couples prevailed as compared to the CG, which showed more variability (p less than 0.01). Within the SG, the before-after BPC comparison revealed a tendency toward more functional couple structures. Fetal outcome and complication rate did not differ between groups. In the SG Cesarean section rate correlated positively, premature birth negatively with age and socio-economic status; complication rate in general correlated positively with couple satisfaction. Couple structure should be recognized in routine pregnancy care, BPC ought to be organized in a way that all different types of couples feel invited. Methodologically, the circumplex model proved to be applicable in obstetrics.