Longitudinal Rates and Risk Factors for Adverse Birth Weight Among First Nations Pregnancies in Alberta.

Objective: We wished to identify the prevalence, longitudinal trends, and associated risk factors for various birth weight categories by First Nations ethnicity in the province of Alberta.

Methods: We performed a retrospective analysis of administrative data for the years 2000 to 2009 inclusive. Age-adjusted prevalence trends for high birth weight (HBW; > 4000g), very HBW (> 4500g), low birth weight (LBW; < 2500g), and very LBW (< 1500g) were compared via average annual percent change analyses. Logistic regression analysis was used to determine risk factors.

Results: First Nations ethnicity was a significant independent predictor of HBW (OR 1.82 [95% CI 1.75, 1.89]), very HBW (OR 2.35 [95% CI 2.18, 2.52]), and very LBW (OR 1.35 [95% CI 1.23, 1.48]), but not of LBW (OR 0.98 [95% CI 0.93, 1.03]). However, HBW prevalence decreased and other birth weight categories remained stable over time in First Nations populations. Gestational diabetes and maternal weight ≥ 91 kg were potentially manageable risk factors for HBW. Potentially manageable risk factors for LBW included pre-gestational renal disease, hypertension, and maternal weight ≤ 45 kg, as well as smoking, illicit drug dependence, and alcohol consumption.

Conclusions: Although HBW, very HBW, and very LBW remain more common in Alberta First Nations populations than in the general population, their prevalence is not increasing.