To help the millions of low-birth-weight babies born every year in the developing world — many of whose mothers don't have access to electricity, let alone incubators — Embrace has designed a small sleeping bag with a heating unit that, after a few minutes in boiling water, maintains a temperature of 98.6°F (37°C) for four-hour stretches. The nonprofit, founded by Stanford students, will sell the $25 warmers to health-care workers, NGOs and mothers, initially in India.