Although the origin and causes of birth control of France in the 18th century have been the subject of discussion as long as 200 years, yet there are no satisfactory explanastions presented. This regrettable situation of the subject may be in part explained from that the problems belong to pre-statistic period and thre was a few vital statistics officially published on which rely the true affairs. As for causes of birth control, we may point out the diversity of the explanations of it. But the incessant, laborious researches into the concerned subject made by I.N.E.D., some results of which appeared as "La prevention des naissances dans la famille, ses origines dans les temps modernes", and the analysis by the method of family reconstitution exploited by Louis Henry and others, contributed to throw light upon the subject. In spite of many monographs and diverse explanations the results are far from the settlement of problems, and we are requested further researches. One of the direction of investigations is without doubt that of historical demography, but as A. Sauvy pointed out, a further research into the documents of penitence reserved at churches and also into the private correspondences as those of Mme Sevigne may be useful.