Fall in the infant mortality rate: the IMR is the number of infants who die before their first birthday, per 1000 babies born alive. this has fallen greatly in the last century. In 1900, it was 154, by 2016 it was 4. This may cause a fall in the birth rate - if infants survive, parents will have fewer of them - reasons for fall: improved housing, sanitation, nutrition, including that of others, knowledge of hygiene and child health