NEW YORK – Women with low vitamin D levels are at significantly increased risk of miscarriage, British researchers have found in a systematic review and meta-analysis.

“Vitamin D is safe and inexpensive, so from a public health point of view supplements are an excellent recommendation. Unfortunately we know that in the UK the absorption of women and pregnant women taking prenatal vitamin supplements remains low, at around 20%,” Dr. Jennifer Tamblyn of the University of Birmingham said in a press release.

“Vitamin D is only really known for its role in late pregnancy complications, but our review also supports another important role for it that could help encourage women about the benefits of taking supplements early,” said Dr. Tamblyn.

The analysis included 10 studies – four randomized controlled trials and six observational studies – with a total of 7663 women.

Women deficient in vitamin D ( 75 nmol/L; odds ratio, 1.94; 95% CI, 1.25 to 3.02), Dr. Tamblyn and colleagues report in Fertility and Sterility.

A pooled analysis comparing women deficient or insufficient in vitamin D (50–75 nmol/L) with women high in vitamin D also found an increased risk of miscarriage (OR, 1.60; 95% CI, 1. 11 to 2.30).

Four randomized controlled trials have assessed the effect of vitamin D treatment on miscarriage, but “study heterogeneity, data quality, and reporting bias precluded direct comparison and meta-analysis” , notes the study team.

The overall quality of the included studies was ‘low’ or ‘very low’ and there was insufficient evidence to accurately assess whether vitamin D treatment reduced the risk of miscarriage.

“New evidence-based interventions are needed for women at risk of miscarriage. Vitamin D deficiency is widespread worldwide, with pregnant women at particular risk,” the researchers write.

“Although traditionally associated with bone disease in mothers and newborns, there is now clear recognition of broader adverse effects, including preterm birth and preeclampsia. Given its excellent safety profile and low cost, even a small effect of vitamin D would be useful when considering an approach to health,” they add.