Anemia is extremely common. Nearly 1 in 4 people worldwide are living with it, making it one of the most widespread health conditions on the planet. As of 2021, roughly 1.9 billion people had anemia, up from about 1.5 billion in 1990. In the United States specifically, about 9.3% of people age 2 and older have anemia.
Global Prevalence by the Numbers
The global prevalence of anemia was 24.3% in 2021. That’s a slight improvement from 28.2% in 1990, but the total number of people affected has actually grown because the world’s population increased faster than rates declined. Progress has been slow and uneven across different countries and regions.
Anemia doesn’t affect everyone equally. Certain groups face dramatically higher rates, and the gap between the most and least affected populations is wide.
Who Is Most Affected
Young children and women of reproductive age carry a disproportionate share of the global burden. According to the World Health Organization, 40% of children between 6 and 59 months old have anemia. That’s roughly 269 million children worldwide. The condition can impair cognitive development and growth during these critical early years.
Among women aged 15 to 49, about 30% are anemic. That number climbs to 37% during pregnancy, when the body’s demand for red blood cells increases sharply to support the growing fetus. In raw numbers, about 539 million non-pregnant women and 32 million pregnant women were affected in 2019.
The reasons these groups are hit hardest come down to biology and nutrition. Menstruation creates ongoing iron loss, pregnancy increases iron and nutrient demands, and young children often have diets that fall short of what their rapidly growing bodies need.
Anemia in Older Adults
Anemia becomes increasingly common with age, but the pattern differs between men and women. CDC data from 2013 to 2016 found that among adults 65 to 74, the prevalence was similar for both sexes: 7.4% in men and 7.6% in women. By age 85 and older, rates jumped dramatically, reaching 39.5% in men and 21.9% in women.
The reversal is notable. Before age 75, women are more likely to be anemic than men. After 75, men overtake women significantly. In older adults, anemia often results from chronic kidney disease, chronic inflammation, nutritional deficiencies, or bone marrow conditions that become more common with aging. It’s frequently underdiagnosed because symptoms like fatigue, weakness, and dizziness overlap with what many people assume is just “getting older.”
Prevalence in the United States
The most recent national data, covering August 2021 through August 2023, puts the overall U.S. anemia prevalence at 9.3% for people age 2 and older. That’s lower than the global average, reflecting better access to nutrition and healthcare, but it still represents tens of millions of Americans.
Rates within the U.S. vary by age, sex, race, and income. The same demographic patterns seen globally hold true domestically: women of childbearing age, young children, older adults, and people with lower incomes or less access to nutrient-rich food are affected at higher rates.
Types and Severity
Iron deficiency is the single most common cause of anemia worldwide. Your body needs iron to produce hemoglobin, the protein in red blood cells that carries oxygen. When iron stores run low, your blood can’t carry oxygen efficiently, leading to the hallmark symptoms of fatigue, pale skin, shortness of breath, and difficulty concentrating. Other causes include deficiencies in vitamin B12 or folate, chronic diseases that interfere with red blood cell production, inherited conditions like sickle cell disease and thalassemia, and blood loss from surgery, injury, or gastrointestinal problems.
Not all anemia is equally serious. The WHO classifies it into three severity levels based on hemoglobin concentration:
- Mild: Hemoglobin slightly below normal. Often causes no noticeable symptoms or only mild fatigue. For non-pregnant women, this means hemoglobin between 110 and 119 g/L; for children 6 to 59 months, between 100 and 109 g/L.
- Moderate: Hemoglobin drops further (80 to 109 g/L in non-pregnant women, 70 to 99 g/L in children). Fatigue, weakness, and shortness of breath during activity become more apparent.
- Severe: Hemoglobin falls below 80 g/L in non-pregnant women or below 70 g/L in children. This level can cause serious complications including heart problems, and it requires prompt treatment.
The vast majority of anemia cases globally are mild or moderate. Severe anemia is less common but concentrated in regions with limited healthcare access, where it contributes to maternal and child mortality.
Why the Numbers Keep Growing
Despite modest improvements in the percentage of people affected, the absolute number of anemia cases rose by more than 400 million between 1990 and 2021. Population growth is the primary driver, particularly in regions of sub-Saharan Africa and South Asia where anemia rates are highest and populations are expanding rapidly.
Other contributing factors include persistent poverty, limited dietary diversity, infectious diseases like malaria and hookworm that destroy red blood cells or cause chronic blood loss, and inadequate public health programs for iron supplementation. Even in wealthier countries, rising rates of chronic diseases like kidney disease and inflammatory conditions contribute to anemia in aging populations. The condition remains one of the most significant nutritional deficiencies worldwide, affecting quality of life, work productivity, and childhood development on a massive scale.