The three proximate determinants are effects of the direct and interactive influences of four preexisting conditions and changes in these

The three proximate determinants are effects of the direct and interactive influences of four preexisting conditions and changes in these, viz. the country’s mortality level, the acceptable number of surviving children, the acceptable sex composition of surviving children, and the costs of postnatal versus prenatal controls on family size and composition. The preexisting conditions and changes in them are, in turn, affected by exogenous influences. Lastly, processes of social interaction can influence the proximate determinants directly and indirectly by interacting with the preexisting conditions and changes.
Maybe most importantly, the model perceives the household as a single unit. It thereby neglects to acknowledge that men and women can have differing fertility interests and that power structures between the sexes determine who dominates fertility decisions – an assertion recognized by Mason herself in a later article (Mason, 2001).