Infant Mortality Rate or IMR is the number of deaths of children under 1 year of age per one thousand live births. This rate for a region is calculated by dividing the number of deaths of children less than 1 year old by the number of live births in a year times 1000. The major causes of congenital infant mortality are sudden infant death syndrome, malformations, accidents, maternal complications during the pregnancy and unintentional injuries. Contributing causes are social and environmental obstacles that prevent availability of basic medical resources. 99% of deaths of infants take place in developing nations. Among these, 86% are caused due to premature births, infections, delivery complications, birth injuries and perinatalasphyxia.
Replacement Rate is the total fertility rate at which women give birth to enough infants in order to maintain the population levels. In case of no female mortality till the culmination of childbearing age (44/45/49), the replacement level of the TFR would be quite near 2.