Estimated Birth Weight at 64th Percentile for Male Infant at 37+5 Weeks
A male infant at 37 weeks + 5 days gestation at the 64th percentile for weight would weigh approximately 3,100-3,200 grams (3.1-3.2 kg).
Weight Assessment Using WHO Growth Standards
The WHO Child Growth Standards provide the most appropriate reference for determining birth weight percentiles, as they were derived from international samples of healthy infants and use rigorous statistical methodologies including the Box-Cox power exponential method to accommodate various distributions 1.
Key Considerations for Late Preterm Infants
Gestational age matters significantly: At 37 weeks + 5 days, this infant is technically term (≥37 weeks) but very close to the late preterm category (34-36 weeks), which carries increased risk for neonatal morbidity and mortality 2.
The 64th percentile indicates above-average weight: This places the infant between the 50th percentile (median) and the 85th percentile, suggesting healthy fetal growth without concerning macrosomia 1.
Weight range estimation: Based on standard growth curves, the 50th percentile at term is approximately 3,000 grams, while the 85th percentile approaches 3,500 grams. The 64th percentile falls proportionally between these values at approximately 3,100-3,200 grams 1.
Clinical Implications
This weight suggests appropriate intrauterine growth for gestational age, which is associated with better neonatal outcomes compared to small-for-gestational-age or large-for-gestational-age infants 2.
Level of care considerations: Even at this gestational age with appropriate weight, close monitoring is warranted as infants born at 35-37 weeks remain at risk for complications including respiratory distress, hypoglycemia, and temperature instability 2.