I am studying the impact of a particular policy on the number of hospitalizations of 1 year old children. My data is collapsed by municipality and a indicator variable for 12 months before vs after the policy took place. My question refers to whether I should weight the regression by the number of 1 year old children. I understand that if I was studying the effect on the hospitalization rate I would do so in order to get a representative population effect. However, I am not sure if I should do so when my dependent variable is an absolute number (and, thus, larger municipalities will tend to have higher number of hospitalizations - hence, this representativeness is already taken into account by construction).