A: The clearest study examining differences between ‘ideal’ (intended) and ‘actual’ (achieved) family sizes is: Heaton, Tim B., Kristen L. Goodman, and Thomas B. Holman. 2001. “In Search of a Peculiar People: Are Mormon Families Really Different?” Pp. 87-117 in Contemporary Mormonism: Social Science Perspectives, 2nd ed. Editors Marie Cornwall, Tim B. Heaton, and Lawrence A. Young. Illinois: University of Illinois Press.
Heaton et. al., on p. 98 (Table 5.4) show that ideal family size for Mormon males is 3.93 children and for Mormon females it is 4.61. This is contrasted to actual family sizes of 2.64 and 2.96 children for Mormon males and females, respectively. To put this into perspective with the rest of the U.S. population (non-Mormons), the ideal family size for males is 2.72 children and for females 2.78 children; actual family sizes are 1.63 and 2.04 for non-Mormon males and females, respectively.