Ross, SusanO'Beirne, MaeveAghajafari, Fariba2016-08-312016-08-3120162016Aghajafari, F. (2016). Vitamin D during Pregnancy (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28658http://hdl.handle.net/11023/3246Vitamin D plays an important role in promoting healthy pregnancy and fetal development. There is a lack of knowledge on (1) the effect of vitamin D deficiency/ insufficiency on pregnancy and neonatal outcomes, (2) the association between maternal plasma vitamin D concentration and dietary intake, and (3) the prevalence of vitamin D deficiency/ insufficiency during pregnancy and the contribution of vitamin D metabolites to estimate vitamin D. This dissertation attempts to address these knowledge gaps about vitamin D during pregnancy. In a systematic review and meta-analysis of observational studies, low maternal 25(OH)D concentrations were found to be associated with higher risks of gestational diabetes (pooled OR 1.49, 95% CI: 1.18 to 1.89), preeclampsia (pooled OR 1.79, 95% CI: 1.25 to 2.58), small for gestational age (SGA) (pooled OR 1.85, 95% CI: 1.52 to 2.26) and lower birth weight (weighted mean difference: -130.92 g (95% CI: -186.69 to -75.14). However, that quality of individual studies was not always optimal due to inconsistent reporting on confounding factors. The two studies in this work involved pregnant women from a large Alberta cohort study to measure vitamin D. 3-epi-25(OH)D3 was found in all of the pregnant women’s blood in mid-pregnancy, at the time of delivery and in cord blood. When the 3-epimer was included in the estimation of status, the prevalence of vitamin D <75 nmol/L was significantly lower (P<0.005). A significant relationship between maternal reported dietary vitamin D intake and plasma 25(OH)D and 3-epi-25(OH)D3 concentration were identified. Consuming the Recommended Dietary Allowance (RDA) (600 IU/ day) was found to be insufficient to achieve vitamin D <75 nmol/L in half of participants. This research highlighted the potentially important association between maternal vitamin D status and pregnancy health and the variability that can arise in study results when different measures of vitamin D status are used. In addition, it extends the literature suggesting that current RDA may not be adequate to ensure that Canadian pregnant women achieving vitamin D status. Furthermore, this research showed that the method employed to measure vitamin D in pregnant women and cord blood can influence the estimates of status.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.EpidemiologyPregnancyNeonatalVitamin DNutirtiondoctoral thesis10.11575/PRISM/28658