In recent decades most countries of the world have seen substantial decline in infant and childhood mortality (UN), however a vast amount of research on this topic, a fraction of which will be presented and discussed below, suggests that the issue of infant and childhood mortality persists, particularly in countries with medium and low Human Development Index (Waldron, Mosley and Chen). In developing countries differentials in survival within a population usually stem from the interacting effects of biological and behavioural factors that influence mortality at different ages, so the data indicating principal cause of death may provide incomplete information. It is therefore important to consider the complex interplay of both biological and social factors that impact intra-population infant and child mortality variations.
It is important to outline some general trends in infant and child mortality at the first place. Infant males have higher mortality rates than females in almost every country or region examined, which is particularly consistent and nearly universal for the neonatal period of one month after birth (Waldron). During later infancy sex differentials become more variable, with females infants experiencing higher mortality in some countries (Lee and Wang 1999), and for young children sex differences in mortality are even more alternating (UN). It was suggested that this happens because males have numerous inherent biological disadvantages such as slow lung maturation, which are most likely to cause death during the neonatal period (e.g. prematurity, respiratory distress syndrome), while females become more vulnerable in later infancy and childhood when behavioural factors such as son preference come into play (Sara Randall, lecture).
But how exactly do these varying trends occur? Mosley and Chen (year) created a framework