Low Birth Weight in South Asia

Intrauterine growth and development is one of the most vulnerable process in the human life cycle and it’s aberrations can result in profound and lasting influence in later life. In the context of developing countries, intrauterine growth has been invariably assessed by birth weight. Although it may be reasonable to infer that fetuses who have experienced growth restriction in utero will be lighter and smaller, it must be understood that size at birth does not completely reflect growth. The suitability of utilizing only birth weight as an indicator of fetal growth has been debated and criticized. However, it is sometimes the only measure available, especially in developing countries. The World Health Organization (WHO), on the basis of world wide data, had recommended that newborns with birth weight less than 2500 g may be considered to fall in the low birth weight (LBW) category carrying relatively greater risks of perinatal and neonatal morbidity and mortality, and substandard growth and development in later life. The validity of this definition and the “cut off point” of 2500 g has been occasionally challenged; but has by and large now gained general acceptance. The latest WHO recommendation has retained this “cut off point” of 2500 g to define LBW and recommended an additional demarcation of 1500 g, to define very low birth weight (VLBW) babies. LBW infants encompass a heterogeneous population of newborns. Broadly, the birth weights may be low because the baby is born small for gestational age (SGA), as a result of intrauterine growth retardation (synonym intrauterine malnutrition) (IUGR) or because birth is preterm. In the developed countries, the overwhelming majority of LBW infants are preterms, whereasin the developing nations, including South Asia, the reverse is the case. The great majority of newborns with LBW are full term infants who are SGA. Attempts have also been made to further classify IUGR as disproportionate or proportionate on the basis of Ponderal index (weight/length3). Disproportionate IUGR infants have a low ponderal index whereas proportionate IUGR babies have a normal ponderal index (all body dimensions proportionately small). On the basis of available evidence, the ensuing sections will examine the nature, consequences and causes of LBW in the South Asian subcontinent and evaluate the various options for action to address this major public health problem in the region.