In 1971, a Health Project was established in order to organize some actions destined for the prevention of perinatal mortality and morbidity. A first examination of these actions was studied in the Rhône-Alpes Region by comparing the results of two surveys, one carried out in 1972 and the other in 1975, both on a representative sample of births. This article successively examines the evolution of morbidity and prevention. The authors note an important improvement in the quality of prevention and a slight progress in the results: perinatal morbidity declined as well as certain signs of fetal distress, while on the other hand, the term and birth weight showed no significant change. In the second part of this article the authors studied the relationships between the socio-cultural characteristics of the parents and the use of prevention measures. They found that certain social inequalities observed in 1972 had decreased while some others increased, new measures seem to be adopted sooner by the higher social classes when they were first envisioned for the interest of better protecting the lower social classes. However, the inequalities diminished for certain fundamental elements of prenatal surveillance, such as the respect for the minimum number of prenatal consultations.