Infant mortality refers to the death of an infant between 1 day and 1 year of age. (Deaths before age 28 days can also be classified as neonatal mortality.) There are many causes of infant mortality, ranging from infections to accidents.
NICHD supports research on many causes of and conditions that can lead to infant death, including Sudden Infant Death Syndrome (SIDS) and other sudden, unexpected infant deaths, birth defects, and preterm birth. The Institute also studies ways to prevent or reduce the risk of these causes and conditions to reduce infant mortality rates and improve infant health outcomes.
About Infant Mortality
What is infant mortality?
Infant mortality is the term used to describe the death of a baby that occurs between the time it is born and 1 year of age. If a baby dies before age 28 days, the death can also be classified as neonatal mortality.
The infant mortality rate—that is, the number of infant deaths out of every 1,000 live births—is an important factor in understanding a population’s overall health because many factors that contribute to infant deaths also affect the health of everyone in a population.1 For example, access to medicine, trained healthcare providers, clean water, and food affect everyone’s health, but can also have a dramatic effect on infant mortality rates.
The term “infant mortality” refers only to deaths that occur after birth. Deaths that occur before birth are usually classified as either stillbirth or pregnancy loss. Stillbirth is the death of a fetus at or after 20 weeks of pregnancy. Pregnancy loss, or miscarriage, is a fetal loss that occurs earlier in pregnancy.
What causes infant mortality?
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
- 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
Are there ways to reduce the risk of infant mortality?
Often, there are no definite ways to prevent many of the leading causes of infant mortality. However, there are ways to reduce a baby’s risk. Researchers continue to study the best ways to prevent and treat the causes of infant mortality and affect the contributors to infant mortality. Consider the following ways to help reduce the risk: