Maternal vitamin D insufficiency and risk of adverse pregnancy and birth outcomes: A systematic review and meta-analysis of longitudinal studies

Abstract

BackgroundThree previous reviews on the association of vitamin D insufficiency in pregnancy with preterm birth (PTB) and stillbirth were limited in scope and deemed inconclusive. With important new evidence accumulating, there is the need to update the previous estimates and assess evidence on other clinically important outcomes such as spontaneous abortion and Apgar score. We conducted a systematic review and meta-analysis to evaluate the quality and strength of the available evidence on the relations between vitamin D nutritional status, and pregnancy and birth outcomes.MethodsPubMed and Scopus databases were searched from their inception to June, 2015 with no language restrictions imposed. Eighteen longitudinal studies satisfied the inclusion criteria. Random effects model was applied in computing the summary effect estimates and their corresponding 95% confidence intervals.ResultsSerum 25(OH)D levels <75 nmol/l was associated with 83% (95% CI: 1.23, 2.74) and 13% (95% CI: 0.94, 1.36) increased risk of PTB measured at <32–34 weeks and <35–37 weeks, respectively. An inverse dose-response relation was observed for both PTB outcome. Serum 25(OH)D levels <75 nmol/l was also associated with 11% increased risk of spontaneous PTB (<35–37 weeks; RR = 1.11; 95% CI: 0.75, 1.65) with a dose-response relation also noted. Vitamin D insufficiency was not associated with risk of spontaneous abortion and stillbirth (RR of 1.04 [95% CI: 0.95, 1.13] and 1.02 [95% CI: 0.96, 1.09], respectively), as well as short gestational length (ES = -0.24, 95% CI: -0.69, 0.22), and low Apgar score.ConclusionsWe found vitamin D insufficiency to be associated with risk of PTB. Regarding spontaneous abortion and stillbirth, the available evidence suggest no association with low vitamin D levels. The evidence on vitamin D nutrition and Apgar score is conflicting and controversial. Overall, the experimental evidence uncovered was small and weak. Hence, the benefits of vitamin D supplementation during pregnancy should be further evaluated through rigorous intervention studies.

The Role of Vitamin D in the Immune System as a Pro-survival Molecule

“…In pregnant women, levels of 25-OH vitamin D 3 o75 nmol/L (ie, o187 ng/mL [ 748 IU]) are considered a risk factor for certain gestational-associated pathologies. 232 Supplementation in pregnant women with 3800 IU of 25-OH vitamin D 3 ( 1 mg of vitamin) produced encouraging results. 233 All breastfed infants, from mothers successfully supplemented with vitamin D, seem to be warranted for a good health in their lives, although controversial data exist.…”

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

“…In addition, observational studies with large sample size have shown the association between maternal VDD during pregnancy and increased risk of pregnancy outcomes (Amegah, Klevor, & Wagner, ; Chen et al, ; Wei, Qi, Luo, & Fraser, ), albeit there are still inconsistencies in this regard (Bodnar et al, ; Bomba‐Opon et al, ).…”

“…The present investigation found that the occurrence of preeclampsia, gestational diabetes, preterm birth, SGA, and caesarean section were not different between groups. The effect of vitamin D supplementation on the pregnancy outcomes including preeclampsia, gestational diabetes, and spontaneous abortion has not been confirmed by several RCTs (Asemi, Karamali, & Esmaillzadeh, 2014b In addition, observational studies with large sample size have shown the association between maternal VDD during pregnancy and increased risk of pregnancy outcomes (Amegah, Klevor, & Wagner, 2017;Chen et al, 2015;Wei, Qi, Luo, & Fraser, 2013), albeit there are still inconsistencies in this regard (Bodnar et al, 2014;Bomba-Opon et al, 2014).…”

Maternal and Foetal Health Implications of Vitamin D Status during Pregnancy

“…Recent meta-analyses of observational studies also support that vitamin D insufficiency (<30 ng/dL) is associated with risk of PTB: PTB (<35-37 week, 20-30 ng/dL) RR 1.24 (95% CI 1.04-1.49), PTB (<35-37 week, <20 ng/ dL) RR 1.36 (95% CI 1.04-1.78), PTB (<32-34 week, <30 ng/dL) RR 1.83 (95% CI 1.23-2.74), PTB (<32-34 week, <20 ng/dL) RR 1.86 (95% CI 1.28-2.68) [59]. With regard to spontaneous abortion and stillbirth, the available evidence suggests that there is no association with low vitamin D levels [59].…”

“…With regard to spontaneous abortion and stillbirth, the available evidence suggests that there is no association with low vitamin D levels [59].…”