 Intrauterine growth restriction IUGR This study defines IUGR as a Z-score for the newborns birth weight for gestational age less than or equal to -2. The study will use the sex-specific Canadian reference for birth weight for gestational age, which uses the 3rd, 5th, 10th, 50th mean, 90th, 95th, and 97th percentiles for 22 to 43 complete weeks and standard deviation Kramer et al, 2001. 