The infant mortality rate is the number of babies who die before their first birthday for every 1,000 born alive. It’s one of the most widely used measures for comparing health across countries and communities, because a single number captures a surprisingly broad picture: the quality of prenatal care, maternal health, nutrition, sanitation, and access to medical resources all feed into it.
How the Rate Is Calculated
The math is straightforward. Take the number of infants who died before age one in a given year, divide it by the total number of live births that same year, then multiply by 1,000. A rate of 5.5, for example, means that roughly 5 or 6 out of every 1,000 babies born alive did not survive to their first birthday.
Health agencies sometimes break this number into two subcategories. Neonatal mortality counts deaths in the first 27 days of life, the period when complications from birth itself and congenital conditions pose the greatest risk. Postneonatal mortality covers deaths from 28 days through 11 months, when causes like sudden infant death syndrome, infections, and injuries become more prominent. Separating the two helps public health officials pinpoint where interventions are most needed.
Why It Matters Beyond Babies
The infant mortality rate is not just a pediatric statistic. The CDC describes it as a reflection of “a wide variety of factors, including access to prenatal care, prevalence of prenatal maternal health behaviors (such as alcohol or tobacco use and proper nutrition during pregnancy), postnatal care and behaviors (including childhood immunizations and proper nutrition), sanitation, and infection control.” In other words, when a country’s infant mortality rate is high, it signals deeper problems in the healthcare system and in living conditions broadly. That’s why economists and public health researchers treat it as a shorthand for societal well-being.
Leading Causes of Infant Death
In the United States, the five leading causes of infant death in 2022 were:
- Birth defects, such as heart abnormalities or genetic conditions present at birth
- Preterm birth and low birth weight, which leave organs underdeveloped
- Sudden infant death syndrome (SIDS), the unexplained death of an otherwise healthy baby during sleep
- Unintentional injuries, including car crashes and suffocation
- Maternal pregnancy complications, such as problems with the placenta or uterus that affect the infant
The relative weight of these causes shifts depending on a country’s income level. In wealthier nations, birth defects and prematurity dominate. In lower-income countries, preventable infections and malnutrition play a much larger role.
How the U.S. Rate Has Changed Over Time
A century ago, infant death was common. In 1916, the U.S. infant mortality rate stood at about 101 deaths per 1,000 live births. By 1940, it had dropped to 47, and by 1950 it was 29.2. That steep decline happened before the widespread use of vaccines or advanced medical technology. Clean water, better sanitation, pasteurized milk, public health nursing, and improved nutrition drove most of the progress.
By 1990, the rate had fallen below 10 per 1,000. The most recent national figure puts it around 5.5 per 1,000 live births. While that’s a dramatic improvement, it still places the U.S. behind many other high-income countries, which cluster closer to 3 or 4 per 1,000.
Racial and Ethnic Disparities in the U.S.
The national average obscures stark differences across racial and ethnic groups. As of 2018 data, the non-Hispanic Black population had an infant mortality rate of 10.8 per 1,000 live births, nearly three times the rate for Asian Americans (3.6) and more than double the rate for non-Hispanic White families (4.6). Native Hawaiian and Pacific Islander communities faced a rate of 9.4, and American Indian families 8.2.
These gaps persist even after controlling for income and education, pointing to systemic factors like unequal access to quality prenatal care, chronic stress from discrimination, and neighborhood-level differences in environmental quality and healthcare infrastructure. The disparities are one reason researchers emphasize that infant mortality is as much a social indicator as a medical one.
How Countries Compare Globally
Globally, infant mortality rates vary enormously. At the country level, neonatal mortality alone ranged from 0.7 deaths per 1,000 live births to 39.4 in 2022. Sub-Saharan Africa carries the highest burden, with a neonatal mortality rate of 27 per 1,000, followed by central and southern Asia at 21. A baby born in sub-Saharan Africa is 11 times more likely to die in the first month of life than one born in Australia or New Zealand, the lowest-mortality region.
These gaps reflect differences in hospital infrastructure, availability of skilled birth attendants, access to antibiotics for newborn infections, and maternal nutrition. Countries that have invested heavily in community health workers and basic obstetric care have seen rapid improvements, sometimes cutting their rates in half within a single decade.