Premature Delivery (Preterm Birth): Definition, Epidemiology, Research & Clinical Management

1. Definition & Classification

Preterm birth is defined as delivery before 37 completed weeks of gestation. It is further classified as:

Globally, about 13.4 million babies were born preterm in 2020—over 1 in 10 births .
Preterm birth remains the leading cause of death among children under 5.
In the U.S., the preterm birth rate increased from 9.8% (2013) to 10.4% (2023).
In 2023, there were approximately 373,900 preterm births in the U.S.
Persistent racial disparities: Black infants (~14.7%) and American Indian/Alaska Native (12.4%) have higher rates than Whites (9.5%) and Asian/Pacific Islanders (9.3%) .

3. Risk Factors & Etiology

Maternal history & demographics: Prior preterm births, multiple gestation, rural residence, low education, prior abortions .
Medical conditions: Hypertension, diabetes, infections (genital tract), PROM, uterine/cervical abnormalities.
Environmental & lifestyle factors: Smoking, poor prenatal care, air pollution, socioeconomic stress, micro plastic exposure (emerging evidence) .

4. Recent Research & Innovations

Study / Intervention	Key Finding	Implication
Blood test (OSU)	Predicts preterm birth before 20 weeks with up to 97.5% accuracy.	Potential for early risk stratification and personalized prenatal care
PreTRM test	Measures two proteins at 18–21 weeks to identify high-risk women (laboratory-developed; available direct-to-consumer)	Helps guide interventions like progesterone, aspirin, closer monitoring
Microplastics in placenta	Higher microplastic levels in placentas from preterm births vs. term (203 vs. 130 µg/g)	Emerging environmental risk factor; further causal research needed
Cord-blood stem cells (Monash)	Umbilical cord blood infusion in extremely preterm infants (<28 and="" appeared="" improved="" in="" neurodevelopment="" preliminary="" safe="" study="" td="" wks="">	Potential new neuroprotective therapy to reduce cerebral palsy risk
Aerosolized surfactant (Endosurf)	Ex vivo model showed effective aerosol delivery of Curosurf with homogeneous lung distribution	May improve treatment of RDS in preterm infants
Artificial womb (EXTEND)	Prototype mimics uterus for extremely preterm babies using amniotic fluid and oxygenator; tested in lambs	Bridge therapy for viability <28 ethics="" evaluation="" human="" pending="" td="" trials="" wks="">

Antenatal corticosteroids:given <34 and="" death="" infection="" ivh="" li="" nec="" neonatal="" rds="" reduce="" risks="" weeks="">
Tocolytics (e.g. β2 agonists, nifedipine, NSAIDs) delay labor by days to allow steroid effect .
Fetal fibronectin (fFN) testing: negative test rules out imminent preterm labor within 7 days; positive results less predictive but helpful in clinical decision-making .
Kangaroo Mother Care: especially effective in low-resource settings; improves thermoregulation, weight gain, infection rates, neurodevelopment, bonding.
Transvaginal ultrasound + cervical circlage (UCL study): detecting C-section scar-related risk; circlage reduced preterm from 15% to 4.1% in high-risk women.

Survivors of preterm birth, particularly extremely preterm, face elevated risks across multiple systems:

Neurodevelopment: cerebral palsy, learning disabilities, sensory deficits .
Chronic conditions: respiratory, cardiovascular, renal, endocrine/metabolic, psychiatric disorders .
Adult mortality: increased all-cause mortality (1.2–1.6×), especially in those born at 22–27 weeks (1.9–4×) .

Topic	Key Take-Home Point
Prevalence	~13 million preterm births globally per year; leading cause of under-5 mortality.
Risk Factors	Medical, socio-economic, environmental (air pollution, microplastics).
Predictive Tools	Immune-based blood test (97.5% accuracy); PreTRM protein test.
Preventive Interventions	Steroids, tocolytics, fFN testing, cervical cerclage, kangaroo care.
Emerging Therapies	Cord-blood stem cells, aerosol surfactant delivery, artificial womb (EXTEND).
Long-Term Risks	Neurological, respiratory, metabolic, renal, cardiovascular, mortality higher through adulthood.

What is the leading global cause of death in children under 5?: Complications of preterm birth remain the top cause worldwide .
Can we predict preterm birth early?: Emerging tests,such as an immune-based blood test (OSU) with up to 97.5% accuracy pre 20 weeks, and Pre TRM at 18–21 weeks,are promising .
Are environmental contaminants involved?: Preliminary data shows elevated micro plastics in preterm placentas; causal links not yet confirmed .
What therapies are emerging to protect preterm infants?: Umbilical cord blood stem cell infusion, aerosolized surfactant via Endo surf, and artificial womb-like systems (EXTEND) are under investigation.
How can clinicians reduce preterm birth risks now?: Use antenatal steroids, tocolytics, fFN testing, cervical circlage in indicated cases, and promote kangaroo care post-birth .