A. Tille, Yule and Christmas, p. 21, etc.
Long before Wargentin, however, Rabelais had shown some interest in this question, and had found that there were most christenings in October and November, this showing, he pointed out, that the early warmth of spring influenced the number of conceptions (Pantagruel, liv. v, Ch. XXIX). The spring maximum of conceptions is not now so early in France.
Villermé, "De la Distribution par mois des conceptions," Annales d'Hygiène Publique, tome v, 1831, pp. 55-155.