New reference curves for head circumference at birth, by gestational age

Area of Science:

• Neonatalogy
• Pediatric Neurology
• Public Health

Background:

• Head circumference (HC) at birth is a key indicator of intrauterine brain development.
• Existing Canadian HC charts are outdated, lack gender specificity, and do not adequately represent lower gestational ages or the current population.

Purpose of the Study:

• To develop current, gender-specific reference curves for head circumference (HC) at birth for Canadian infants.
• To provide a more accurate tool for assessing fetal brain development across a wide range of gestational ages (GAs).

Main Methods:

• Combined data from the Canadian Neonatal Network (CNN) and McGill's Obstetrical Neonatal Database (MOND).
• Included data for GAs from 23 to 41 weeks, excluding non-singletons and infants with congenital anomalies.
• Utilized penalized spline regression for statistical smoothing of birth weight and HC data.

Main Results:

• Generated gender-specific curves using data from 39,896 births.
• Found that current weight curves align with existing Canadian references.
• Demonstrated significant underestimation and misclassification of infants' HC percentiles when using older or international references.

Conclusions:

• Developed up-to-date, gender-specific HC reference curves for Canadian infants (23-41 weeks GA).
• These curves accurately reflect the current Canadian population, including a substantial number of very premature infants.
• The new curves offer improved accuracy for assessing neonatal head growth and brain development.