What is the definition of the preterm (premature) delivery period?

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From the Guidelines

Preterm delivery is defined as birth between 20 0/7 and 36 6/7 weeks of gestation. This definition is crucial in identifying individuals at risk for preterm delivery and providing appropriate management to reduce adverse neonatal complications 1. The preterm period can be further categorized into different sub-periods, including extremely preterm, very preterm, and moderate to late preterm.

  • Extremely preterm: less than 28 weeks
  • Very preterm: 28 to less than 32 weeks
  • Moderate to late preterm: 32 to less than 37 weeks Understanding these categories is essential in guiding clinical decision-making and optimizing outcomes for preterm infants. According to the study by the Society for Maternal-Fetal Medicine 1, approximately three-fourths of all preterm births occur in the late preterm period, which is between 34 0/7 and 36 6/7 weeks of gestation. The management of preterm labor includes interventions such as antenatal corticosteroids to accelerate fetal lung maturity, magnesium sulfate for neuroprotection, and tocolytic medications to delay delivery when appropriate. These interventions are critical in reducing neonatal morbidity and mortality associated with preterm birth. The use of antenatal corticosteroids, in particular, has been shown to substantially reduce the risks of adverse neonatal complications, including death, respiratory distress syndrome, intraventricular hemorrhage, and sepsis, when administered to pregnant women with a high likelihood of preterm delivery before 34 weeks of gestation 1.

From the Research

Definition of Preterm Delivery

The definition of preterm delivery is birth that occurs between 20 0/7 weeks and 36 6/7 weeks of gestation 2. This definition is crucial in identifying pregnancies at risk and providing appropriate management to reduce the risk of neonatal morbidity and mortality.

Key Characteristics of Preterm Delivery

  • Preterm delivery is the leading cause of neonatal morbidity and mortality 3, 4, 5
  • Approximately 5-10% of all births are premature 4
  • Preterm labor is associated with various risk factors, including preterm rupture of membranes, cervical incompetence, and infections 4

Gestational Age and Preterm Delivery

  • The gestational age at which preterm delivery occurs is critical in determining the management and outcomes of the pregnancy 5, 2
  • Births that occur before 37 weeks of gestation are considered preterm 5, 2
  • The American College of Obstetricians and Gynecologists defines preterm birth as birth between 20 0/7 weeks and 36 6/7 weeks of gestation 2

Importance of Defining Preterm Delivery

  • Defining preterm delivery is essential in identifying pregnancies at risk and providing appropriate management to reduce the risk of neonatal morbidity and mortality 3, 4, 5, 2
  • Accurate definition and diagnosis of preterm delivery can help healthcare providers make informed decisions about the management of the pregnancy and the timing of delivery 5, 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Antenatal Steroids and Tocolytics in Pregnancy.

Obstetrics and gynecology clinics of North America, 2023

Research

Tocolysis: A Review of the Literature.

Obstetrical & gynecological survey, 2019

Research

Preterm delivery: an overview.

Acta obstetricia et gynecologica Scandinavica, 2003

Research

Preterm Labor: Prevention and Management.

American family physician, 2017

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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