This paper examines son preferences by specifying sex composition by birth order of existing
children as key independent variables. The results indicate a lexicographic preference for a
son by mothers aged 50 years and older. Mothers without a son are also under substantial
pressure to bear more children and shorten their birth spacing. However, once a family
includes a son, parents do not consider sex composition over other decisions on family size
and fertility timing. It would appear that the preference for a son is relatively stronger for
some birth orders in the northern regions of Vietnam but slightly weaker in the Central
Highlands and South Central Coast. In addition, while women are important in the
Vietnamese labor force, the level of preference for sons does not differ across income at
lower birth orders. We also obtain mixed results for son preferences if we include mothers
less than 50 years of age in our analysis