What is the primary reason for hospitalization in the United States?

September 22, 2025 •

3 min read

According to recent data, while many people might assume heart attacks or injuries, the leading principal diagnosis for non-maternal, non-neonatal stays is actually septicemia. This article will delve into what is the primary reason for hospitalization in the United States, providing a clear breakdown of the top diagnoses and the factors that influence them.

Quick Summary

The primary reason for hospitalization varies depending on whether maternal and neonatal stays are included. Overall, childbirth is the most common reason for admission, but septicemia is often the leading principal diagnosis for all other adult stays.

Key Points

Childbirth and Newborns: The most common reason for hospitalization in the U.S. when all ages are considered, accounting for a large percentage of overall admissions.
Septicemia: The leading principal diagnosis for hospital stays among non-maternal and non-neonatal patients.
Chronic Diseases: Heart failure, osteoarthritis, and diabetes with complications are among the top five diagnoses and contribute significantly to hospital stays, especially among older populations.
Influencing Factors: Age, chronic illness prevalence, and socioeconomic status all influence the most frequent reasons for admission.
Dynamic Trends: The primary reasons for hospitalization have shifted over time, highlighting the importance of up-to-date health data and research.

Understanding Hospitalization Statistics

Statistics on hospitalizations can sometimes be complex, as the 'primary reason' can be viewed from different perspectives. Analyzing the data requires separating broad categories like childbirth from specific medical diagnoses in other age groups. Leading health organizations like the Agency for Healthcare Research and Quality (AHRQ) and the Centers for Disease Control and Prevention (CDC) track these trends, providing crucial insights into public health.

The Leading Causes of Inpatient Stays

The Most Common Reason Overall: Childbirth

When looking at the total number of hospital stays, including all age groups, childbirth and related conditions consistently rank as the most frequent reason for hospitalization in the United States. A 2021 Kaiser Family Foundation (KFF) report found that maternal and neonatal stays accounted for a significant portion of all hospitalizations in 2021. This highlights the importance of obstetrics and gynecology services in the overall healthcare landscape.

The Leading Medical Diagnosis: Septicemia

If maternal and neonatal stays are excluded, septicemia emerges as the leading principal diagnosis for hospital admissions among adults. Septicemia, or sepsis, is a severe and life-threatening complication of an infection. Its high prevalence can be attributed to several factors, including the increasing age of the population, a rise in antibiotic-resistant infections, and a higher rate of chronic illnesses that weaken the immune system. Sepsis is also one of the costliest diagnoses, placing a significant economic burden on the healthcare system.

A Deeper Look into Other Top Diagnoses

Beyond childbirth and septicemia, several other conditions frequently lead to hospital admissions across different age groups and demographics.

Cardiovascular Conditions

Diseases of the heart and circulatory system are major drivers of hospitalization. Heart failure is a top-ranking diagnosis, especially among the elderly. Other common cardiovascular issues include acute myocardial infarction (heart attack) and cardiac dysrhythmias. The high burden of these chronic diseases makes cardiovascular care a central focus of inpatient services.

Musculoskeletal Disorders

Conditions affecting the muscles and skeleton also contribute significantly to hospital stays. Osteoarthritis, a degenerative joint disease, is a frequent diagnosis, particularly among older adults. Joint replacement surgeries, which often follow from severe osteoarthritis, are a common reason for inpatient care.

Respiratory Illnesses

Respiratory issues, like pneumonia and Chronic Obstructive Pulmonary Disease (COPD), also cause a substantial number of hospitalizations, especially during flu season. The severity of these conditions often necessitates intensive medical intervention that can only be provided in a hospital setting.

Endocrine and Metabolic Diseases

Diabetes mellitus with complications is another top reason for hospital admission. When blood sugar levels are poorly managed, it can lead to severe issues like diabetic ketoacidosis, infections, or organ damage requiring inpatient care.

Mental Health and Substance Abuse

Mental health and substance abuse disorders are significant contributors to hospitalization, particularly for younger adults. Acute episodes of conditions like major depressive disorder or complications from substance use often require a period of inpatient stabilization and treatment.

Comparison of Top Diagnoses (Excluding Maternal/Neonatal Stays)

This table provides a snapshot of some of the most frequent principal diagnoses based on a 2018 AHRQ report, highlighting their frequency and cost.


Rank	Diagnosis	Number of Stays (2018)	Aggregate Cost (2018)
1	Septicemia	2,218,800	$41.5 billion
2	Heart Failure	1,135,900	$14.5 billion
3	Osteoarthritis	1,128,100	$18.0 billion
4	Pneumonia	740,700	$7.7 billion
5	Diabetes with Complication	678,600	$12.5 billion

The Evolving Landscape of Hospital Admissions

The leading causes of hospitalization have shifted over time due to advancements in medicine and changes in population health. For example, some historical data showed conditions like pneumonia at the top, while more recent studies reflect the rise of septicemia. The COVID-19 pandemic also had a significant impact on hospitalization patterns, with an increase in respiratory admissions and notable shifts in discharge patterns. Continual monitoring and analysis of these trends are vital for public health officials and hospital administrators to allocate resources effectively.

Conclusion

In summary, the answer to what is the primary reason for hospitalization in the United States depends on the patient population being considered. While childbirth represents the single most common reason overall, septicemia is the top principal diagnosis for non-maternal, non-neonatal stays. Chronic conditions such as heart failure and musculoskeletal issues also play a substantial role. Understanding these complex patterns is crucial for addressing the diverse healthcare needs of the nation's population and managing the significant costs associated with inpatient care.

For more information on healthcare data and research, you can explore the Healthcare Cost and Utilization Project (HCUP) from the Agency for Healthcare Research and Quality (AHRQ).

Frequently Asked Questions

Excluding maternal stays, septicemia (blood poisoning) is often cited as the leading principal diagnosis for adults. However, heart failure and other cardiovascular conditions also rank very highly, particularly for older adults.

Yes, childbirth and newborn care are typically classified as inpatient hospital stays. When included in overall statistics, childbirth is the single most common reason for hospitalization across the entire population.

Infectious diseases are a major driver of hospitalizations. Aside from septicemia, conditions like pneumonia are consistently among the most frequent principal diagnoses, especially for certain age groups.

Yes, mental health and substance abuse disorders are significant reasons for inpatient admissions, especially among younger adults. Acute episodes of severe depression or bipolar disorder often require hospital care for stabilization.

Over the past several decades, the leading causes have shifted. For instance, septicemia has increased its ranking significantly, becoming the number one principal diagnosis for many non-maternal, non-neonatal stays, while pneumonia has become less frequent.

Chronic conditions such as heart failure, Chronic Obstructive Pulmonary Disease (COPD), and complications from diabetes mellitus consistently rank among the most common reasons for hospital stays, particularly for older adults managing these long-term illnesses.

Hospitalization costs depend on many factors, including the length of stay, required treatments, and the severity of the condition. For example, stays for complex conditions like septicemia often require more resources and are therefore more expensive than stays for less complex issues.