By the early 1870s, the child mortality rate of the area of modern-day Bangladesh was estimated to be just over five hundred deaths per thousand live births, meaning that more than half of all infants born in these years would not survive past their fifth birthday. Child mortality would steadily climb towards the end of the 19th century, to a rate of almost 57 percent, as a series of famines would result in significant declines in access to nutrition and the increased displacement of the population. However, after peaking at just over 565 deaths per thousand births at the turn of the century, the British colonial administration partitioned the Bengal region (a large part of which lies in present-day India), which would begin to bring some bureaucratic stability to the region, improving healthcare and sanitation.
Child mortality would largely decline throughout the 20th century, with two temporary reversals in the late 1940s and early 1970s. The first of these can be attributed in part to disruptions in government services and mass displacement of the country’s population in the partitioning of India and Pakistan following their independence from the British Empire; during which time, present-day Bangladesh became East Pakistan. The second reversal would occur in the early 1970s, as a side effect for the Bangladesh Liberation War, the famine of 1974, and the subsequent transition to independence. Outside of these reversals, child mortality would decline significantly in the 20th century, and by the turn of the century, child mortality in Bangladesh would fall below one hundred deaths per thousand births; less than a fifth of the rate at the beginning of the century. In the past two decades, Bangladesh's child mortality has continued its decline to roughly a third of this rate, due to improvements in healthcare access and quality in the country; in 2020, it was estimated that for every thousand children born in Bangladesh, almost 97 percent will survive past the age of five years.