Hypothermia contributes to a significant portion of neonatal deaths. Kangaroo Mother Care (KMC) is a safe and effective method of warming; however, it is not always feasible, for example in settings such as resuscitation or clinical instability. Electric warmers are the standard of care in developed countries, but are extremely costly, complicated with risk of causing both hypo and hyperthermia with misuse, and often not reliable in settings without stable electricity. After two encouraging pilot studies totaling 204 uses in 2 district hospitals and 4 health centers in rural Rwanda, the investigators aim to further study the warmer in a stepped wedge prospective controlled trial in hospital setting to assess safety and efficacy of the Infant Warmer based on clinical observation and feasibility based on observer audits.

Hypothermia contributes to a significant portion of neonatal deaths. Kangaroo Mother Care (KMC) is a safe and effective method of warming; however, it is not always feasible, for example in settings such as resuscitation or clinical instability. Electric warmers are the standard of care in developed countries, but are extremely costly, complicated with risk of causing both hypo and hyperthermia with misuse, and often not reliable in settings without stable electricity. The Infant Warmer the investigators propose to study has previously been tested in 2 pilot studies totaling 204 uses, occurring in 2 district hospitals and 4 health centers in rural Rwanda.

The combined results of these pilot studies were extremely encouraging. This study will be a stepped wedge prospective controlled trial in hospital setting to assess safety and efficacy of the Infant Warmer based on clinical observation, and feasibility based on observer audits. A total of 10 district hospitals will participate in the study. All 10 hospitals will start with a 2 week period of observation in which "pre" data will be collected. Hospitals will then receive the warmer and be transitioned to the "post" period at a rate of one every two weeks. The primary study aim is to assess the safety, efficacy and feasibility of the Infant Warmer as an addition to KMC, and to achieve and maintain euthermia when KMC is inadequate or unavailable. The study will be conducted across a wide range of district hospitals with control data coming from pre-intervention period and treatment data coming from post intervention period, with the intervention being the introduction of the Infant Warmer.

Inclusion Criteria:

Any infant with the following criteria for whom caregiver not available for KMC, or KMC is not adequate (less than 0.5°C/hour rise in temperature):

1. Axillary temperature < 36.5 °C

   a) If an electric warmer is available and the infant's temperature is < 35°C, then the infant will start by being warmed on the electric warmer until the infant's temperature reaches 36°C, then can start non-electric Infant Warmer use.

2. Infants at-risk for hypothermia (criteria: estimated post-menstrual age of < 35 weeks or current body weight of < 2.5 kg).

Exclusion Criteria:

1. Any infant whose family is unwilling to consent to the study.
2. Mothers who are critically ill at the time of infant eligibility or deemed not medically stable by nursing staff to be approached for consent.
3. Any infant with a contraindication to KMC (medical instability) and electrical heating source available.
4. Any infant with initial temperature < 35°C and electrical heating source available.
5. Infants requiring phototherapy.
6. Infants with significant skin condition.

Stop Criteria:

If an electric heating source is available, the infant will be taken off of the study and warmed with an appropriate source of electric heat if the infant:

1. If an electric heating source is available, the infant will be taken off of the study and warmed with an appropriate source of electric heat if the infant:

   i. Has temp < 36 °C while receiving maximum non-electric heat exposure and temperature decreases on any measurement ii. Has temp < 36 °C while receiving maximum non-electric heat exposure and temperature does not begin to rise within 30 minutes iii.Has temp < 36 °C while receiving maximum non-electric heat exposure and not heating at a rate of > ½ °C per hour until temperature >36.5°C iv.Has a temperature that falls below 36°C despite maximum non-electric heat exposure

   Definition of maximum non-electric heat exposure:

   1. IW, KMC, hat; if KMC available
   2. IW, blanket, hat; if KMC not available
   3. Blanket, hat; while seeking caregiver for KMC and/or preparing IW if KMC and IW not available

2. Has temperature > 37.5 °C

3. Is ever considered to be too severely ill by the medical team to be safely cared for in the non-electric Infant Warmer.

4. The warmer will be removed once its temperature drops below phase change temperature as assessed by noting that the material begins to harden and turn white and is no longer warm in area under where baby is lying.