Dietary Patterns and Gestational Weight Gain in the Alberta Pregnancy Outcomes and Nutrition Study

Abstract

Inappropriate weight gain during pregnancy is associated with adverse health outcomes for both mother and baby. In 2010, Health Canada adopted the Institute of Medicine's guidelines on gestational weight gain (GWG). This study explored the extent to which dietary patterns reported in the 2nd trimester of pregnancy were associated with adherence to Health Canada's (2010) guidelines for total GWG. The Alberta Pregnancy Outcomes and Nutrition study (APrON) is a prospective cohort of women recruited and followed through pregnancy and the post‐partum period. Total GWG for each woman (n=2067) was calculated by subtracting pre‐pregnancy weight from highest weight in pregnancy. Women were categorized by pre‐pregnancy BMI (self‐reported pre‐pregnancy weight (kg)/measured height (m)2) and whether total GWG was below, met or exceeded the guidelines. Diet was assessed by 24‐hour recall in the 2nd trimester and foods/beverages were coded into 51 food groups based on nutritional similarity. Principal components analysis was run on the energy adjusted food groups. For components which accounted for the greatest variance, a dietary pattern score was calculated by multiplying each woman's standardized consumption (g/day) of each food group by the corresponding coefficient for the component and summing. Scores were expressed as a z‐score, with a mean of zero and standard deviation of one. Associations between dietary pattern scores and adherence to GWG guidelines were assessed using multinomial logistic regression. Table 1 shows proportions of women who were below, met or exceeded the guidelines by pre‐pregnancy BMI group. Three main dietary patterns were identified in this cohort: (i) ‘Healthy’, (3.8% of the variance) was characterized by higher intakes of fruits, vegetables, wholemeal bread, and lower intakes of high‐energy soft drinks, processed meat and white‐bread; (ii) ‘Refined Carbs’ (3.3% of the variance) was characterized by higher intakes of rice and pasta, added sugar, breakfast cereal and white bread, and lower intakes of wholemeal bread; and (iii) ‘Tea and Toast’ (3.1% of the variance), was characterized by higher intakes of tea and coffee, added sugar, full‐fat milk and white bread. In the unadjusted models, relative to women who met the guidelines, the odds of exceeding the guidelines were lower in women with higher ‘healthy’ diet scores (OR 0.71, 95% CI: 0.52, 0.96). This association was observed only in women with a pre‐pregnancy BMI in the overweight group, and it became non‐significant when adjusted for educational attainment. Neither the ‘Refined Carbs’ nor ‘Tea and Toast’ patterns were associated with GWG in any of the pre‐pregnancy BMI categories. Dietary patterns analysis can be a useful tool in observational studies. However, assessing the impact of diet on GWG is challenging and further research is needed to account for measurement error when using single 24 hour recalls for dietary assessment.Support or Funding InformationThis project is funded by the Interdisciplinary Team Grants Program of Alberta Innovates‐Health Solutions (AI‐HS) Proportions of women who were below, met or exceeded the GWG guidelines according to their pre‐pregnancy BMI category Pre‐pregnancy BMI category Underweight (n(%)) Normal weight (n(%)) Overweight (n(%)) Obese (n(%)) Below guidelines 16 (26) 257 (23) 25 (7) 28 (15) Met guidelines 30 (48) 403 (37) 82 (23) 35 (19) Exceeded guidelines 16 (26) 443 (40) 256 (70) 125 (66)