Calcium and Vitamin D Intake During Pregnancy and Postpartum in the Alberta Pregnancy Outcomes and Nutrition (APrON) Study

  • Author / Creator
    Weinberg, Amy R.
  • Calcium and vitamin D are important in maintaining a healthy pregnancy. Low intake/status has been associated with preeclampsia, preterm delivery, lower birth weight, poor fetal skeletal growth, reduced bone mass, and excessive maternal bone loss. Rarely have these nutrients been examined together in intake studies during pregnancy and postpartum. The primary research objective was to describe calcium and vitamin D intake across pregnancy and 3 months postpartum in a large cohort of women (n~1054) in Alberta. The secondary objective was to identify the sources of calcium and vitamin D in the diet of the cohort. The cohort consisted of older women (mean: 31 ± 5 years old) with a healthy BMI (24.2 ± 4.7), and high socioeconomic status. Diet (24-hour recall) and supplement intakes were collected up to 3 times (once during each trimester) and 3 months postpartum and analyzed using Food Processor and a supplement database. Estimated calcium intake came mainly from diet whereas vitamin D mainly came from supplements. Estimated mean vitamin D supplement intake in this cohort was higher than reported in the literature. Estimated mean calcium intake (diet, supplement, and total) increased with each trimester, however, was significantly lower at 3 months postpartum (p< 0.05). Estimated mean vitamin D from food/beverages intake did not change through pregnancy and postpartum, but supplement and hence total intake increased significantly with each trimester and at 3 months postpartum (p< 0.05). The cohort met the EAR for calcium with diet only, but 20% of women did not meet the EAR at 3 months postpartum. At all time points, women did not meet the EAR for vitamin D with diet alone and relied on supplement intake to meet recommendations. Despite this, 23% of women in the first trimester and postpartum still did not meet the EAR for vitamin D. Without ‘adequate’ vitamin D intake, calcium cannot be absorbed as well. In the cohort, 19-34% of women had either intake below the EAR for calcium or vitamin D intake below the EAR, placing them at risk. Of women that exclusively breast fed, 71% met the EAR for total calcium and these women were 2.9 times (95% CI: 1.67-4.8, p< 0.001) more likely to meet the EAR than those that exclusively formula fed. Of women that exclusively breast fed, 81% met the EAR for total vitamin D and these women were 2.3 times (95% CI: 1.37-4.0, p= 0.002) times more likely to meet the EAR than those that exclusively formula fed. There was a moderate (r= 0.47, p< 0.001) correlation between caloric intake and estimated calcium intake and no correlation between caloric intake and estimated vitamin D intake (r= 0.09, p< 0.001). Supplement users (SU) had significantly higher estimated mean total vitamin D intake (921.8 ± 126.2 IU) than non-supplement users (NSU) (212.1 ± 16 IU) at all four time points (p< 0.05). Aerobic exercise, planned pregnancy, ethnicity, and weight change status were identified as predictors of calcium intake and aerobic exercise, marital status, and income were found to significantly affect a woman’s ability to meet the EAR for vitamin D. While calcium fortified foods and beverages minimally contributed to estimated dietary intake, vitamin D fortified foods/beverages majorly contributed to intake. As high as 40% of estimated vitamin D in the diet came from vitamin D fortified cow’s milk and 9% came from other fortified sources such as juices, plant-based beverages, and margarine. Medium to high milk drinkers (> 250 mL/day) were significantly (p< 0.001) more likely to meet the EAR than women that drank no milk. In conclusion, the women in this cohort met calcium recommendations with diet but depended on supplement intake to meet vitamin D recommendations. Milk drinkers were more likely to meet the recommendations than non-milk drinkers. Women may be at greater risk for suboptimal calcium status due to decreased absorption from low vitamin D intake. The postpartum period was a time where estimated calcium intake decreased and further education emphasizing the importance of increasing both nutrient intakes may need to be done to ensure women are meeting recommendations for bone loss prevention. Future studies may include incorporating vitamin D status as well as examining the relationship between dietary intake and maternal and infant health outcomes.

  • Subjects / Keywords
  • Graduation date
    Fall 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.