Low birth weight (LBW) refers to neonates born weighing less than 2,500 g (5½ lb). Two main groups are affected:

• Premature neonates: Born before 37 weeks of gestation but appropriate for their gestational age. They likely would have achieved normal weight if carried to term.

• Small for gestational age (SGA) neonates: Born at term or preterm but weighing less than the expected amount for gestational age. Their organs are usually mature, but intrauterine growth has been restricted.

Differentiating between these groups helps determine the underlying cause and guides management. LBW is associated with higher morbidity and mortality — affected neonates are up to 20 times more likely to die in the first month of life. Some SGA infants achieve catch-up growth by 8–12 months, while others remain below the 10th percentile. For premature neonates, weight should be corrected for gestational age until about 24 months.

Emergency interventions

• Monitor respiratory status continuously. Watch for:

  • Apnea

  • Grunting respirations

  • Intercostal or xiphoid retractions

  • Respiratory rate >60/min after the first hour of life

• Provide respiratory support as needed:

  • Supplemental oxygen via hood or nasal CPAP

  • Endotracheal intubation if severe distress or apnea

• Maintain thermal stability:

  • Use an overbed warmer or incubator (Isolette).

  • Cover the neonate’s head.

  • If no incubator is available, use a wrapped warm-water bottle, avoiding overheating.

• Observe closely for signs of hypothermia, which increases oxygen consumption and worsens distress.

History and Physical Examination

History

• Maternal health: hypertension, diabetes, infections, nutritional status, substance use.

• Antenatal course: infections (rubella, CMV, varicella), placental problems, poly/oligohydramnios, preterm labor.

• Delivery details: gestational age, complications, mode of delivery.

Physical Examination

• Estimate gestational age using a validated tool (e.g., New Ballard Score).

• Assess neuromuscular tone and skin maturity.

• Record birth weight, length, and head circumference.

• Look for:

  • Signs of prematurity (thin skin, lanugo, soft ear cartilage, absent sole creases).

  • SGA features (wasted appearance, thin cord, little subcutaneous fat).

  • Dysmorphic features or skin lesions indicating congenital infection or chromosomal anomalies.

• Auscultate for heart murmurs, abnormal lung sounds, or bowel sounds.

Medical causes of low birth weight

Special considerations

• Nutrition:

  • Initiate feeds promptly (breast milk preferred).

  • Feed every 2–3 h; use gavage or IV nutrition for very ill or extremely preterm neonates.

• Gastrointestinal monitoring:

  • Measure abdominal girth daily; watch for distension or blood in stool (risk of necrotizing enterocolitis).

• Infection surveillance:

  • Monitor temperature, feeding tolerance, behavior, respiratory pattern, and episodes of apnea.

  • Perform sepsis workup if infection is suspected.

• Metabolic monitoring:

  • Check glucose frequently; treat hypoglycemia promptly.

• Oxygen therapy:

  • Titrate carefully; avoid prolonged high concentrations to reduce retinopathy of prematurity risk.

• Urine output:

  • Weigh diapers; assess urine for blood, glucose, or protein.

• Jaundice:

  • Observe for yellowing of skin or sclera; treat hyperbilirubinemia early.

Patient Counseling

• Explain the meaning of low birth weight and its causes.

• Reassure parents that many LBW neonates thrive with good care.

• Teach them:

  • How to maintain warmth (skin-to-skin “kangaroo care”).

  • Early and frequent feeding techniques.

  • Warning signs (apnea, poor feeding, hypothermia, jaundice).

• Encourage bonding and involvement in care to enhance attachment.

References

1. Ballard JL. New Ballard Score expanded to include extremely premature infants. J Pediatr. 1991;119(3):417–23.

2. Gogia S, Sachdev HS. Neonatal vitamin A supplementation for prevention of mortality and morbidity in infancy: Systematic review of randomized controlled trials. BMJ. 2009;338:919.

3. Wang YZ, Ren WH, Liao WQ, Zhang GY. Concentrations of antioxidant vitamins in maternal and cord serum and their effect on birth outcomes. J Nutr Sci Vitaminol. 2009;55(1):1–8.