The United States faces a significant challenge in maternal healthcare, with rising rates of serious complications during and immediately following pregnancy. Severe Maternal Morbidity (SMM) is a measure used to track these life-threatening events that occur during labor, delivery, or the postpartum period. Understanding SMM is a public health imperative because it represents an opportunity to intervene and prevent permanent health consequences or death. Focusing on the causes and identification of these severe events allows healthcare systems to implement targeted improvements to make childbirth safer for all women.
Defining Severe Maternal Morbidity
Severe Maternal Morbidity refers to unexpected outcomes of labor and delivery that result in significant short- or long-term consequences to a woman’s health. This definition encompasses a range of conditions and complications that, if not treated swiftly, could lead to death. SMM is often described as a “near-miss” event, signifying a woman who survived a life-threatening complication associated with pregnancy or childbirth. SMM is tracked because it is far more common than maternal mortality, occurring 50 to 100 times more frequently. Annually, approximately 50,000 to 60,000 women experience SMM in the United States, making it a powerful indicator of maternal care quality. The health consequences of SMM can be profound, often leading to extended hospital stays and lasting physical or psychological trauma.
How SMM is Clinically Identified
Public health organizations, such as the Centers for Disease Control and Prevention (CDC), use a standardized index to track SMM based on administrative hospital discharge records. This index uses specific diagnostic and procedure codes to identify severe events. The CDC’s index includes 21 indicators that fall into two main categories: specific severe diagnoses and specific life-saving interventions.
Specific Severe Diagnoses
Specific diagnoses qualify as SMM if they represent severe end-organ damage or systemic failure. These signal that the woman’s body experienced a serious, systemic event that posed an immediate threat to her life. Examples include:
- Acute heart failure
- Septic shock
- Eclampsia
- Amniotic fluid embolism
Life-Saving Interventions
The second category tracks interventions necessary when a patient is in a critical state and requires immediate stabilization. These procedures demonstrate that a critical, life-saving effort was required to prevent death. Markers include:
- Massive blood transfusion (receiving four or more units of blood products)
- Unplanned hysterectomy (often performed to control unstoppable postpartum hemorrhage)
- Temporary mechanical ventilation (indicating assistance was required due to organ failure)
Primary Medical Causes and Risk Factors
The severe events constituting SMM are typically triggered by a few leading medical conditions arising during pregnancy or the postpartum period. The most frequent clinical cause is severe hemorrhage, or excessive bleeding, which can lead to dangerously low blood volume and shock. Disorders related to high blood pressure, such as severe preeclampsia and eclampsia, are major drivers, potentially causing stroke, seizures, and organ damage. Infections, particularly sepsis, can rapidly become life-threatening if not diagnosed and treated promptly. Cardiac events and cardiovascular complications, including cardiomyopathy, are also significant causes. These four conditions—hemorrhage, hypertension, infection, and cardiac issues—account for the majority of SMM cases.
Biological Risk Factors
Certain patient characteristics increase the biological risk of experiencing SMM. Advanced maternal age (35 years or older) is associated with higher risk. The presence of pre-existing chronic conditions, such as diabetes, obesity, and cardiovascular disease, also substantially elevates the likelihood of a severe complication. A history of prior C-section delivery is an established risk factor for complications in subsequent pregnancies.
Addressing Health Disparities in SMM
SMM is not distributed equally across the population, showing profound disparities along racial and ethnic lines. Data consistently show that certain groups, particularly Black women, experience SMM at significantly higher rates compared to non-Hispanic white women. This gap persists even when controlling for income, education, and pre-existing medical conditions, suggesting the root causes are systemic.
Structural racism and its manifestation in the healthcare system contribute heavily to these differences. Implicit bias among providers can lead to women of color receiving delayed or substandard care, including the underestimation of symptoms or lack of timely intervention. Chronic stress from structural racism also negatively affects physiological health, potentially worsening underlying conditions like hypertension. Socioeconomic barriers often limit access to high-quality prenatal and postpartum care in underserved areas. Addressing these disparities requires confronting the underlying issues of healthcare equity and access.
Systemic Approaches to Prevention
Preventing SMM requires a coordinated effort across policy, clinical practice, and public health surveillance. A major initiative involves implementing standardized emergency protocols, known as “safety bundles,” in labor and delivery units nationwide. These bundles provide clear, evidence-based guidelines for managing the most common causes of SMM, such as obstetric hemorrhage and severe hypertension. State-level Maternal Mortality Review Committees (MMRCs) play a crucial role by confidentially reviewing SMM cases to identify contributing factors and determine preventability. The findings inform policy changes and quality improvement efforts at hospitals. Extending postpartum care coverage, such as through expanded Medicaid eligibility, helps ensure women receive necessary follow-up care for up to a year after delivery, preventing post-birth complications from becoming severe.