Abstract: Population control policies keep on attracting massive attention: having more children would directly contribute to household’s poverty. Using household level data from Nepal, we investigate the links between household’s fertility decisions and variations in their size and composition. We show that the relationships between household size and additional births is positive among young mothers, but becomes negative as mothers grow older. Couples with fewer children host, on average, more other relatives on the longer run. This result implies that reductions in a household’s fertility have an ambiguous impact on its per capita consumption which depends on how the household’s composition responds to new births. We use the gender of the first born child to instrument the total number of consecutive children and to identify the causal relationship.