As a country becomes healthier, what is most likely to happen regarding childhood mortality?

A healthier country means there is a low chance of getting sick. The advancement in medicine, as well as taking care of oneself helps mortality decline.
According to WHO, a child's risk of dying is highest during their first month of life.  To prevent this risk, a mother prior to birth of her child can take immunization and antenatal care consultations, and avoid smoking and alcohol. This increase the chance of survival of the baby. However, it doesn't stop there. Essential care is still needed once the child is born because they are still prone to illness.