To describe temporal trends in fetal "growth" and to examine the roles of sociodemographic, anthropometric, and other determinants.
Hospital-based cohort study of 61,437 nonmalformed singleton live births at 22 to 43 weeks' gestational age. Four main measures were examined: (1) birth weight, (2) birth weight-for-gestational-age Z score, (3) small-for-gestational-age (SGA), and (4) large-for-gestational age (LGA), with the latter 3 measures based on a recently developed population-based Canadian reference. Gestational age was based on the last normal menstrual period if confirmed (+/- 1 week) by early ultrasonogram.
The mean birth weight and Z score increased significantly (P or =37 weeks, with a corresponding reduction in % SGA and a rise in % LGA. No consistent trends were seen among births 34 to 36 or