Newborn
Overview
A newborn (neonate) generally refers to an infant within 28 days after birth, a period of rapid adaptation to the extrauterine environment. This period is physiologically, neurologically, and immunologically very vulnerable, but also marked by rapid growth and development. Newborns begin to function independently in all organ systems, including respiration, circulation, temperature regulation, and nutrition, during which various physiological changes and adaptive phenomena occur. Newborn care and health assessment are very important as they form the foundation for later infant and child health.
Main Content
Classification of Newborns
Newborns are classified according to gestational age and birth weight. Those born before 37 weeks of gestation are preterm, 37–42 weeks are full-term, and over 42 weeks are post-term. Based on birth weight, infants under 2,500 g are classified as low birth weight, and those over 4,000 g as large for gestational age. This classification is key to determining the health risks and management plan for the newborn.
Physiological Characteristics of Newborns
- Respiration: The first breath begins immediately after birth, with a respiratory rate of 30–60 breaths per minute, which can be rapid and irregular. Alveolar expansion and surfactant secretion are important.
- Circulation: Transition from fetal circulation to adult-type circulation occurs, with closure of the ductus arteriosus and foramen ovale. Heart rate is 120–160 beats per minute.
- Temperature Regulation: Due to low subcutaneous fat and large body surface area, maintaining body temperature is difficult. Non-shivering thermogenesis using brown fat is the main heat source.
- Digestion: Stomach capacity is small (30–90 ml), intestinal peristalsis is rapid, and colostrum and breastfeeding are recommended. Meconium is passed within 24–48 hours after birth.
- Immunity: IgG is transferred from the mother, but IgA, IgM, etc., are low, making the newborn vulnerable to infection. Breastfeeding provides additional immunity.
- Nervous System: Primitive reflexes (Moro reflex, sucking reflex, grasping reflex, etc.) appear and gradually disappear. Vision is focused at a distance of 20–30 cm.
Newborn Screening Tests
Within 48–72 hours after birth, screening tests for congenital metabolic disorders and diseases are performed. Representative tests include phenylketonuria, congenital hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis, hearing screening, and congenital heart disease screening (pulse oximetry). Early detection and treatment can prevent serious developmental disorders.
Neonatal Jaundice
Physiological jaundice appears on the 2nd to 4th day after birth and resolves within 1–2 weeks, caused by delayed bilirubin metabolism due to liver immaturity. However, pathological jaundice (onset within 24 hours, high levels, prolonged duration) should raise suspicion of hemolytic disease, liver disease, infection, etc., and may require phototherapy or exchange transfusion.
Newborn Nutrition
Breastfeeding is recommended, with colostrum rich in immunoglobulins and nutrients. Feeding frequency is every 2–3 hours, 8–12 times a day, with the amount gradually increasing. For formula feeding, proper concentration and hygiene are important. Vitamin D supplementation is recommended.
Newborn Care
- Cord Care: Keep the umbilical cord dry and clean, and monitor for signs of infection (redness, discharge).
- Bathing: Pay attention to maintaining body temperature, and bathe gently with lukewarm water.
- Sleep: Place the infant on the back to sleep to prevent Sudden Infant Death Syndrome (SIDS).
- Vaccination: Hepatitis B vaccine, BCG, etc., are administered within the first month of life.
Neonatal Diseases
- Respiratory Distress Syndrome: Common in preterm infants, caused by alveolar collapse due to surfactant deficiency.
- Neonatal Sepsis: Systemic inflammatory response due to infection; early diagnosis and antibiotic treatment are important.
- Neonatal Hypoglycemia: Blood glucose below 40 mg/dL, with symptoms such as tremors, lethargy, and seizures.
- Congenital Heart Disease: Detected by cyanosis, tachypnea, heart murmurs, etc.
Recent Trends
As of 2024–2025, the following changes and trends are notable in the field of neonatal medicine:
- Targeted Gene Therapy: Gene therapy for congenital metabolic diseases (e.g., spinal muscular atrophy) is being applied in the neonatal period, increasing the potential for fundamental treatment.
- Advances in Preterm Infant Care: Survival rates for extremely low birth weight infants (under 1,000 g) have improved, and early intervention programs for neurodevelopmental support are expanding.
- Breastfeeding Promotion Policies: The WHO and UNICEF 'Baby-Friendly Hospital' initiative is spreading, emphasizing immediate skin-to-skin contact and colostrum feeding after birth.
- Digital Health Monitoring: Wearable devices (oxygen saturation, heart rate, respiratory monitors) are used in neonatal intensive care units, enabling real-time data-based management.
- Microbiome Research: Research on the impact of the neonatal gut microbiome on immune development and long-term health, such as allergies and obesity, is active, and the use of probiotics is increasing.
- Prenatal Diagnosis and Early Intervention: Non-invasive prenatal testing (NIPT) and genomic analysis are becoming common for early detection of congenital diseases and establishing treatment plans immediately after birth.
Related Topics
- [[Preterm Infant]]
- [[Breastfeeding]]
- [[Sudden Infant Death Syndrome]]
- [[Congenital Metabolic Disorders]]
- [[Neonatal Intensive Care]]
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