Vitamin D and its impact on maternal-fetal outcomes in pregnancy: A critical review

Abstract

The role of vitamin D beyond its classical function in calcium homeostasis has been of significant interest in recent years. There has been expanding research on the pleiotropic role of vitamin D in pregnancy and the implications of its deficiency on maternal-fetal outcomes. Several studies have associated low maternal vitamin D status to adverse outcomes in pregnancy, including preeclampsia, gestational diabetes, preterm births, low birth weight, and others. Several randomized controlled clinical trials of Vitamin D supplementation during pregnancy have also been conducted. Though some of the studies found improvement in pregnancy outcomes with vitamin D supplementation, others have not shown any association. In this article, we have critically reviewed the observational and interventional studies, published primarily within the past two years (January 2014 to February 2016) on the influence of vitamin D deficiency on pregnancy and the impact of its supplementation. The potential underlying mechanisms of vitamin D in regulating each of the outcomes have also been discussed.

Maternal Vitamin D Status among Different Ethnic Groups and Its Potential Contribution to Adverse Pregnancy and Child Outcomes

“…Systematic reviews and meta-analysis, including cross-sectional, longitudinal, cohort, ecological, and observational studies, indicate inconsistent results regarding the association between vitamin D deficiency and PET. Some studies reported an increased risk of PET women with vitamin D deficiency in pregnancy in contrast with others [43][44][45]. This contradiction of finding can be explained by different vitamin D assessment methods, criteria applied to define vitamin D deficiency, different season and trimester in studies [44].…”

“…Moreover, the immune cell regulation role of vitamin D protects β-cells from damaging and improves its function [50,51]. Although vitamin D deficiency can be associated with the pathogenesis of diabetes mellitus type 1 and type 2, its role in GDM is not conclusive [43]. Conflicting results have been found in case-control, prospective cohort studies, and reviews looking into the risk of GDM with vitamin D status [46].…”

“…Conflicting results have been found in case-control, prospective cohort studies, and reviews looking into the risk of GDM with vitamin D status [46]. Some review studies indicate that pregnant women with significant lower 25(OH)D had a higher risk of GDM by 40-60% [45,52], while in systematic and critical reviews, most studies failed to support the association between vitamin D status and GDM prevention [43,44]. Thus, more large-scale prospective studies are needed to evaluate this association.…”

“…There are conflicting findings regarding the effect of Vitamin D on preterm delivery. Some articles including critical and narrative reviews, reported no association between vitamin D deficiency and preterm delivery [43,46,76,77], while single studies, systematic review, and meta-analysis showed significant relationship between them [45,[78][79][80][81]. Inconsistent findings can be explained by different designs of each study including the timing of 25(OH)D assessment, and different definition of preterm delivery.…”

Efficacy of two different doses of oral vitamin D supplementation on inflammatory biomarkers and maternal and neonatal outcomes

“…Some of these are gestational diabetes mellitus and preeclampsia in mother (Abedi, Mohaghegh, Afshary, & Latifi, 2014), small for gestational age (SGA), low birth weight, and respiratory problems like wheezing and asthma in child (Newhook et al, 2009). Of the adverse birth outcomes associated with vitamin D deficiency (VDD), preterm delivery, abortion, and caesarean section can be mentioned (Agarwal, Kovilam, & Agrawal, 2018;Wei, 2014).…”