PretermEdit
Preterm birth, defined as birth before the 37th week of gestation, is a major public health concern because it is the leading cause of death in newborns in many parts of the world and a frequent source of long-term disability. The spectrum of preterm birth spans from late preterm (34 0/7 to 36 6/7 weeks) to very preterm (28 0/7 to 31 6/7 weeks) and extreme preterm (before 28 weeks). Outcomes improve with each week of gestation, but advances in neonatal care have substantially increased survival and reduced morbidity for many preterm infants. The condition is the product of complex interactions among maternal, fetal, placental, and environmental factors, and it is influenced by access to prenatal care, social determinants of health, and broader health policy environments. gestational age preterm birth neonatal intensive care unit
The term preterm encompasses both medically indicated preterm births, where delivery is recommended for maternal or fetal health reasons, and spontaneous preterm births, which arise from spontaneous labor or rupture of membranes. In high-income countries, prevention and management have benefited from standardized guidelines, advances in maternal-fetal medicine, and improvements in neonatal technology, yet disparities persist across and within countries. antental corticosteroids and other interventions are routinely deployed to improve fetal lung maturity in imminent preterm births, while postnatal care in the NICU aims to support organ development and reduce complications. tocolysis neonatal intensive care unit]
Medical and biological aspects
Definition and classification
Preterm birth is typically classified by gestational age at birth into: - late preterm: 34 0/7 to 36 6/7 weeks - very preterm: 28 0/7 to 31 6/7 weeks - extreme preterm: less than 28 weeks These categories help guide prognosis and clinical management. The term also relates to birth weight categories, such as low birth weight, which often accompanies preterm delivery but is not synonymous with gestational age. gestational age low birth weight
Causes and risk factors
Preterm birth results from a mix of obstetric, maternal, fetal, and environmental factors. Known risk factors include: - a history of prior preterm birth - multiple pregnancies (twins, triplets, and higher-order multiples) - maternal infections and inflammation - chronic maternal conditions (hypertension, diabetes, kidney disease) - uterine or cervical abnormalities - acute stressors such as trauma or severe illness - lifestyle factors, including smoking and substance use - limited access to quality prenatal care and social determinants of health (e.g., poverty, housing instability)
Despite extensive study, many preterm births occur with no clear, singular cause. Ongoing research seeks to identify biological pathways—such as placental insufficiency or inflammatory signaling—that could be targeted to prevent spontaneous preterm birth. maternal health placenta intrauterine infection
Diagnosis and clinical management
Diagnosis hinges on accurately dating the pregnancy (often via ultrasound) and monitoring for signs of labor or cervical shortening. When preterm birth is anticipated or imminent, clinicians employ several strategies: - antenatal corticosteroids (e.g., betamethasone) to accelerate fetal lung development in fetuses at risk of delivery within 7 days - magnesium sulfate for neuroprotection in certain cases of extreme preterm birth - tocolytics to delay delivery briefly, allowing steroids and transfer to a facility with appropriate neonatal care - management of maternal conditions (blood pressure, diabetes, infections) to reduce complication risk - planning for delivery in a facility with a NICU and neonatal specialists
After birth, the infant may require specialized NICU care to support breathing, temperature regulation, nutrition, and infection prevention. Long-term follow-up focuses on neurodevelopment, growth, vision, and hearing, given the higher risk of complications such as respiratory distress syndrome, intraventricular hemorrhage, and retinopathy of prematurity. tocolysis neonatal intensive care unit respiratory distress syndrome intraventricular hemorrhage retinopathy of prematurity neurodevelopment
Prevention and public health approaches
Prevention emphasizes both medical care and broader social supports. Evidence supports: - early and regular prenatal care to identify and manage risk factors - maternal vaccination, nutrition, and management of chronic diseases - smoking cessation programs and reduction of harmful exposures during pregnancy - addressing social determinants such as housing, food security, and access to care
Policy discussions around prevention often intersect with political and economic perspectives. Many right-leaning or market-oriented frameworks emphasize expanding access to high-quality prenatal and maternal care through private-sector involvement, encouraging personal responsibility, and prioritizing cost-effective interventions. Critics of broader social determinants-focused narratives argue that while structural factors matter, practical interventions that are scalable and evidence-based—such as improved prenatal screening, timely transfer to specialized centers, and support for families after birth—offer the most efficient route to reducing preterm births and improving outcomes. Proponents of a more expansive social determinants approach counter that without addressing root causes like poverty and chronic stress, medical advances alone cannot close disparities. The debate centers on how to balance individual accountability with systemic reform, and on how to allocate finite resources for maximum population health impact. prenatal care public health policy paid family leave social determinants of health
Outcomes and long-term considerations
Short-term neonatal outcomes
Survival rates improve with each additional week of gestation, but extreme and very preterm infants remain at risk for complications such as: - respiratory and cardiac problems - neurological injuries - feeding and growth challenges - infection
Advances in NICU technology, surfactant therapy, and supportive care have substantially reduced mortality and severe morbidity for many preterm infants. However, even among those who survive the neonatal period, long-term risks include neurodevelopmental delays, school-age learning challenges, and motor impairments. Ongoing follow-up and early intervention services are important components of care. neonatal intensive care unit surfactant therapy neurodevelopmental disorders
Long-term outcomes and life course
Longitudinal studies track outcomes into childhood and beyond, highlighting the importance of early support, family resources, and access to continued medical and educational services. Economic and social costs—such as parental time off work and long-term health care needs—remain relevant considerations for health systems and policymakers. perinatal mortality long-term outcomes
Ethical and policy considerations
Scarce neonatal resources force difficult decisions at times, particularly in units with high volumes of extreme preterm births. This raises questions about equity, triage, and the balance between aggressive treatment and quality of life. The policy debate intersects with debates over parental rights, the role of government in health care, and the most effective ways to reduce preterm births across diverse populations. neonatal care ethics health policy