Definition of Newborn Age
A newborn is defined as an infant from birth through the first 28 days of life (0-27 days). This definition is supported by medical guidelines and is critical for appropriate care classification.
Age Classification of Infants
- The newborn period (neonatal period) encompasses the first 28 days (0-27 days) of life 1
- This period is further divided into:
- Immediate newborn: First hours after birth
- Early newborn: First week of life
- Late newborn: From 7-27 days 1
Clinical Significance of the Newborn Period
Physiological Considerations
- Newborns undergo critical physiological transitions during this period:
- Cardiorespiratory adaptation from fetal to extrauterine life
- Thermoregulation stabilization
- Feeding establishment 1
- Vital signs in the newborn period have specific normal ranges:
- Axillary temperature: 36.5°C to 37.4°C (97.7–99.3°F)
- Respiratory rate: Below 60 per minute without distress
- Heart rate: 100-190 beats per minute when awake; as low as 70 beats per minute when sleeping 1
Care Level Designations
- Level I facilities (well newborn nurseries) provide care for healthy term newborns and stable preterm infants at 35-37 weeks' gestation 1
- Level II facilities care for moderately ill newborns ≥32 weeks' gestation or ≥1500g 1
- Level III facilities care for infants <32 weeks' gestation, <1500g, or with medical/surgical conditions 1
- Level IV facilities provide the highest level of care for the most complex and critically ill newborns 1
Special Considerations for Newborn Care
Discharge Criteria
- Discharge readiness for healthy term newborns should be based on:
- Stable vital signs for 12 hours preceding discharge
- At least 2 successful feedings
- Normal physical examination
- Appropriate laboratory screening tests completed 1
Screening and Monitoring
- All newborns should be assessed for risk of severe hyperbilirubinemia before discharge 1
- Universal newborn screening includes testing for hearing loss, genetic conditions, metabolic disorders, and critical congenital heart disease 2, 3
- Newborns require close monitoring for jaundice, especially in the first 24 hours 1
High-Risk Newborns
- Periviable births (20 0/7 to 25 6/7 weeks) require specialized care and counseling 1
- Early-term births (37-38 weeks) have higher mortality rates compared to full-term births (39-42 weeks) 4
- Very preterm infants (24-28 weeks) require intensive monitoring and intervention to reduce mortality and morbidity 5
Clinical Implications
- The 28-day newborn period represents a time of heightened vulnerability requiring specialized care protocols 1
- Proper classification of newborn age ensures appropriate level of care assignment and follow-up scheduling 1
- Healthcare providers should be vigilant about age-specific risks and interventions during this critical period 1, 2