Infant mortality is efined as the number of deaths of infants (one year of age or younger) per 1000 live births. The most common cause of infant mortality worldwide has traditionally been dehydration from diarrhea. Because of the success of spreading information about Oral Rehydration Solution (a mixture of salts, sugar, and water) to mothers around the world, the rate of children dying from dehydration has been decreasing and has become the second most common cause in the late 1990s. Currently the most common cause is pneumonia. Major causes of infant mortality in more developed countries include congenital malformation, infection and SIDS.