Neonatal hypothermia is recognized as contributing to mortality and morbidity, but data are largely lacking from low-resource settings in developing countries where the majority of high-risk neonates are born. The overall goal of this secondary data analysis is to estimate the incidence, risk factors, and health consequences of hypothermia among newborns in a rural population of southern Nepal. The data sets that will be used to address these issues derive from two large community-based trials undertaken between 1998 and 2005. Together, these studies followed 27,000 newborns from birth to 28 days, recording axillary temperature up to 11 times during home visits as a covariate for the primary outcomes of neonatal mortality and infection. The aims of the proposed analyses include the following: 1) Estimation of the timing and incidence of mild, moderate, and severe hypothermia through the neonatal period and examination of maternal, neonatal, and newborn care factors associated with hypothermia. Key measures of potential risk factors include birth weight, gestational age, and thermal care practices such as bathing, drying, wrapping, oil massage, and skin to skin contact. Daily ambient temperature data are available and will be correlated with axillary temperature measures to examine seasonality of hypothermia risk. 2) Quantify the subsequent risk of mortality and morbidity associated with neonatal hypothermia. Prospectively collected vital status data through 28 days will allow comparison of mortality risk between hypo- and normo- thermic infants, and assessment of the variability in risk by severity and timing of hypothermia. Verbal autopsy data are available for all neonatal deaths and risk regression models will be adjusted for a wide range of potential confounding variables. The risk of probable sepsis defined using an algorithm composed of direct and indirect signs of morbidity collected at each home-visit will also be compared with hypothermic status. 3) Assess the impact of varying the current WHO definitions for mild, moderate, and severe hypothermia on the quantified incidence, risk factors and consequences of hypothermia. The overall incidence and attributable risk estimates of associated factors will be compared across alternate definitions. These analyses will fill an important gap in our understanding of the burden and impact of hypothermia on neonatal mortality and morbidity in low-resource settings. Conclusions will inform upon the design of community-based neonatal care programs that include behavior change components that aim to reduce hypothermia and improve thermal care. Examination of alternate cutoffs for defining hypothermia severity may improve design of low-cost technologies for identification and subsequent management of hypothermic infants in the community. [unreadable] [unreadable] [unreadable]