Vitamin D and miscarriage: a systematic review and meta-analysis

Area of Science:

• Reproductive Endocrinology
• Nutritional Science
• Obstetrics & Gynecology

Background:

• Maternal vitamin D status is crucial for pregnancy outcomes.
• Suboptimal vitamin D levels are increasingly recognized as a potential risk factor in pregnancy complications.
• Understanding the link between vitamin D and miscarriage is vital for reproductive health strategies.

Purpose of the Study:

• To determine the association between maternal vitamin D status and the risk of miscarriage.
• To evaluate if vitamin D supplementation can reduce the incidence of miscarriage or recurrent miscarriage (RM).

Main Methods:

• A systematic review and meta-analysis of randomized and observational studies were conducted.
• Searched major databases (MEDLINE, Embase, CINAHL, Cochrane) from inception to May 2021.
• Included studies investigating maternal vitamin D levels and miscarriage risk, or vitamin D treatment and miscarriage outcomes.

Main Results:

• Ten studies (7,663 women) were included: 4 RCTs and 6 observational studies.
• Vitamin D deficiency (<50 nmol/L) was linked to a higher miscarriage risk (OR, 1.94; 95% CI, 1.25-3.02).
• Combined analysis showed vitamin D insufficiency and deficiency increased miscarriage risk (OR, 1.60; 95% CI, 1.11-2.30).

Conclusions:

• Vitamin D deficiency and insufficiency are significantly associated with an increased risk of miscarriage.
• The efficacy of preconception vitamin D treatment in preventing pregnancy loss requires further investigation due to study limitations.
• Overall study quality was rated as low to very low, highlighting the need for high-quality research.