Understanding Preterm Birth: Causes, Risks, and Impact

Preterm birth, defined as a baby born alive before 37 completed weeks of pregnancy, remains a significant global health challenge. In 2022, preterm birth affected approximately 1 in every 10 infants born in the United States, with a recorded rate of 10.4%.

The World Health Organization reported that an estimated 13.4 million babies were born preterm in 2020. Globally, prematurity is the leading cause of death in children under the age of 5 years.

Classifications and Timing of Birth

Healthcare providers categorize preterm births based on gestational age. According to the World Health Organization, these categories include:

• Extremely preterm: less than 28 weeks
• Very preterm: 28 to less than 32 weeks
• Moderate to late preterm: 32 to 37 weeks

While preterm birth is defined as occurring before 37 weeks, healthcare providers consider a pregnancy to be full term only when childbirth occurs at 39 weeks or later. Unless there is a medical necessity, delivery should not be scheduled before 39 weeks of pregnancy.

Health Risks and Complications

Critical growth for the brain, lungs, and liver occurs during the final weeks and months of pregnancy. When a baby is born too early, these organs may not be fully developed, leading to serious health risks.

Infants born preterm may experience breathing problems, feeding difficulties, and trouble maintaining their body temperature. Some may require specialized care in a Neonatal Intensive Care Unit (NICU).

Long-term complications can include cerebral palsy, developmental delays, and problems with vision, and hearing. In 2022, preterm birth and low birth weight accounted for approximately 14.0% of infant deaths in the United States.

Contributing Factors and Disparities

Preterm birth can occur spontaneously or due to medical indications that require an early induction of labor or a caesarean birth. Causes may include infections, multiple pregnancies, and chronic conditions such as high blood pressure and diabetes.

Certain demographic and social characteristics are associated with higher rates of preterm birth. These include teenagers and women who become pregnant over the age of 35.

Racial and ethnic disparities persist in the United States. According to CDC data from 2022, the preterm birth rate among Black women was 14.6%, which was approximately 50% higher than the rates for White women (9.4%) or Hispanic women (10.1%).

Prevention and Management

Preventing preterm birth is challenging because the causes are not always fully understood. However, the CDC notes that pregnant women can take specific steps to reduce their risk and improve general health.

• Getting prenatal care early and continuing it throughout the pregnancy.
• Quitting smoking.
• Avoiding the use of alcohol and drugs.

For those experiencing signs of preterm labor, seeing a healthcare provider immediately is critical. Medical intervention may be available to improve the health of the baby at birth.

Survival rates for preterm infants vary significantly by region. In high-income countries, nearly all babies born at or below 32 weeks survive. In low-income settings, approximately half of these infants die due to a lack of basic care, such as breastfeeding support, warmth, and treatment for breathing difficulties and infections.