<Li> Neonatal mortality is newborn death occurring within 28 days postpartum . Neonatal death is often attributed to inadequate access to basic medical care, during pregnancy and after delivery . This accounts for 40--60% of infant mortality in developing countries . </Li> <Li> Postneonatal mortality is the death of children aged 29 days to one year . The major contributors to postneonatal death are malnutrition, infectious disease, troubled pregnancy, Sudden Infant Death Syndrome and problems with the home environment . </Li> <P> Causes of infant mortality directly lead to the death . Environmental and social barriers prevent access to basic medical resources and thus contribute to an increasing infant mortality rate; 99% of infant deaths occur in developing countries, and 86% of these deaths are due to infections, premature births, complications during delivery, and perinatal asphyxia and birth injuries . Greatest percentage reduction of infant mortality occurs in countries that already have low rates of infant mortality . Common causes are preventable with low - cost measures . In the United States, a primary determinant of infant mortality risk is infant birth weight with lower birth weights increasing the risk of infant mortality . The determinants of low birth weight include socio - economic, psychological, behavioral and environmental factors . </P> <P> Causes of infant mortality that are related to medical conditions include: low birth weight, sudden infant death syndrome, malnutrition and infectious diseases, including neglected tropical diseases . </P>

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