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Vitamin D and risk of preterm birth: Up‐to‐date meta‐analysis of randomized controlled trials and observational studies
Author(s) -
Zhou ShanShan,
Tao YongHao,
Huang Kun,
Zhu BeiBei,
Tao FangBiao
Publication year - 2017
Publication title -
journal of obstetrics and gynaecology research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 1341-8076
DOI - 10.1111/jog.13239
Subject(s) - medicine , observational study , randomized controlled trial , meta analysis , pediatrics , obstetrics
Aim We performed a meta‐analysis of randomized controlled trials (RCT) and observational studies to answer the two following questions: (i) whether low maternal circulating 25 hydroxyvitamin D (25‐OHD) is associated with an increased risk of preterm birth (PTB) or spontaneous PTB (sPTB); and (ii) whether vitamin D supplementation alone during pregnancy can reduce the risk of PTB. Methods Literature search was carried out using Pubmed, Web of Science and Embase databases up to June 2016. Pooled OR or relative risk (RR) with 95%CI were computed using fixed or random effects models depending on the size of heterogeneity. Subgroup analysis was used to explore potential sources of between‐study heterogeneity. Publication bias was evaluated using Egger's test and Begg's test. Results Twenty‐four articles (six RCT and 18 observational studies) were identified. Maternal circulating 25‐OHD deficiency (pooled OR, 1.25; 95%CI: 1.13–1.38) rather than insufficiency (pooled OR, 1.09; 95%CI: 0.89–1.35) was associated with an increased risk of PTB, and vitamin D supplementation alone during pregnancy could reduce the risk of PTB (pooled RR, 0.57; 95%CI: 0.36–0.91). This was also the case for the sPTB subgroup (circulating 25‐OHD <50 vs >50 nmol/L; pooled OR, 1.45; 95%CI: 1.20–1.75). Conclusions Maternal circulating 25‐OHD deficiency could increase PTB risk and vitamin D supplementation alone during pregnancy could reduce PTB risk. Extrapolation of the results, however, must be done with caution, and there is urgent need for larger, better‐designed RCT to confirm this effect.