An analysis of birth weight by gestational age in Canada

Area of Science:

• Pediatrics
• Neonatology
• Public Health

Background:

• Accurate birth-weight-gestational-age standards are crucial for identifying infants requiring specialized care and for understanding intrauterine growth retardation.
• Existing standards were often limited by small sample sizes, outdated data, or lack of specificity regarding birth type and infant sex.

Purpose of the Study:

• To develop current, population-based Canadian birth-weight-gestational-age standards specific to birth type (singleton/twin) and sex.
• To compare birth weight data from 1972 and 1986 to assess changes and establish updated reference ranges.

Main Methods:

• Analysis of live birth data from Canada for the years 1972 and 1986.
• Calculation of 10th, 50th, and 90th percentile birth weights stratified by gestational age, birth type, and sex.

Main Results:

• For term deliveries (≥37 weeks gestation), percentile birth weights were slightly higher in 1986 compared to 1972.
• For preterm deliveries (<37 weeks gestation), birth weight percentiles remained largely unchanged between 1972 and 1986.
• Updated standards were established for singleton and twin infants, differentiated by sex.

Conclusions:

• The developed Canadian standards provide a reliable, up-to-date reference for assessing infant growth.
• These standards will improve clinicians' ability to accurately diagnose and manage deviations in intrauterine growth, whether retardation or acceleration.