"Statistics on differentials in the proportion of mothers expecting to have additional children and in the average number of additional children expected, according to selected demographic and socioeconomic characteristics. Based on data collected by a questionnaire mailed to mothers for a sample selected from records of births in 1964, 1965, and 1966 which were filed with the National Center for Health Statistics."
"February 1972."
Description based on online resource, PDF version; title from cover (CDC, viewed July 23, 2018).