Gender of Infants Conceived on Different Days of the Menstrual Cycle

To the Editor: I think that some questions must be raised about Dr. Harlap's study in the June 28 issue. Mothers were interviewed on the first day post partum concerning the length of the last three menstrual cycles before conception. No confirming interviews were given at a later time. It is now well documented that recall of the length of cycles is generally very poor^1,2; it is probably not better after labor, anesthesia, analgesia, and blood loss. Of the three cycles “the mid-point” was selected as the typical cycle length — perpetuating the fictitious determination of cycle length. The.