Infant and child mortality rates refer to the measure of the number of deaths of infants and children under the age of five, often expressed per 1,000 live births. These rates are critical indicators of overall public health and wellbeing in a society, reflecting the effectiveness of healthcare systems, maternal health, and socio-economic conditions. High mortality rates during the 18th century indicated significant challenges such as poor medical knowledge, lack of sanitation, and inadequate nutrition affecting children.