There are many different causes of infant mortality, from infection to birth defects or accidents. The main causes of infant mortality in the United States are different than the main causes of infant death around the world. In addition, in the United States and worldwide, the most common causes of infant death in the first weeks after birth are different than those that occur later in the first year.
There is a difference between causes of infant mortality and contributors to infant mortality. A cause leads directly to a death. In contrast, a contributor is a risk factor that makes the death more likely to happen. Learn more about the risk factors for infant mortality.
Causes of Infant Mortality in the United States
The most common causes of death in the United States in 2011 were the following:1
- Birth defects
- Preterm birth and low birth weight
- Sudden Infant Death Syndrome (SIDS)
- Pregnancy complications
The causes of infant mortality in the United States have changed somewhat over the past several decades. In 1980, birth defects, SIDS, preterm birth/low birth weight, and pregnancy complications were among the top five causes of death, as they are now. At that time, respiratory distress syndrome (RDS), instead of accidents, was also on the top-five list.2 However, with the development of treatments for RDS, deaths from this cause have declined significantly.
Overall, the rate of infant death in the United States has dropped during the last several decades.
Causes of Infant Mortality Worldwide
Globally, the top five causes of infant death in 2010 (the most recent year for which data were available) were the following:3,4
- Neonatal encephalopathy, or problems with brain function after birth. Neonatal encephalopathy usually results from birth trauma or a lack of oxygen to the baby during birth.
- Infections, especially blood infections
- Complications of preterm birth
- Lower respiratory infections (such as flu and pneumonia)
- Diarrheal diseases
This ranking is an average for all infant mortality from birth to age 1 year. It does not reflect the fact that the major causes of death in older infants are different from those in younger infants. For example, birth defects are a top cause of death worldwide in the days just after birth, but not among older infants. In contrast, malaria is a top cause of death around the world in infants older than 1 month of age, but not in younger infants.3,4
The top five causes of global infant mortality were the same for 2010 as they were for 1990. However, deaths from certain causes dropped dramatically in those 20 years. In particular, many fewer babies died of lower respiratory infections and diarrheal diseases in 2010 than did in 1990.3,4