One-carbon metabolism is crucial for the maintenance of healthy pregnancy and alterations in this pathway have been associated with various pregnancy-related complications. Therefore, the present study was conducted to test the hypothesis that the altered folic acid, vitamin B12 and homocysteine levels are associated with the risk of early pregnancy loss (EPL). Plasma folic acid, vitamin B12 and homocysteine levels were analyzed in 83 females with EPL and 70 healthy pregnant females in their first trimester. Further, meta-analyses of folic acid, vitamin B12 and homocysteine were also performed involving various eligible studies. Results from our case-control study and meta-analysis showed that folic acid deficiency is not associated with the risk of EPL. On the other hand, low vitamin B12 and hyperhomocysteinemia were individually found to be significant risk factors for EPL in the present study (P < .01, P < .05, respectively) and meta-analysis as well (P < .001, P < .05, respectively). Vitamin B12 deficiency in combination with hyperhomocysteinemia was a more serious risk factor for EPL (Odds Ratio = 4.98, P = 0.002). Therefore, we conclude that vitamin B12 deficiency and elevated homocysteine levels are independent risk factors for EPL, and of higher risk when combined. The assessment of vitamin B12 and homocysteine levels may serve as a good screening marker for EPL risk.

一碳代谢对于维持健康妊娠至关重要，该途径的改变与各种妊娠相关并发症有关。因此，本研究旨在检验叶酸、维生素 B12 和同型半胱氨酸水平改变与早孕流产 (EPL) 风险相关的假设。对 83 名 EPL 女性和 70 名健康怀孕女性在妊娠早期的血浆叶酸、维生素 B12 和同型半胱氨酸水平进行了分析。此外，还对各种符合条件的研究进行了叶酸、维生素 B12 和同型半胱氨酸的荟萃分析。我们的病例对照研究和荟萃分析的结果表明，叶酸缺乏与 EPL 风险无关。另一方面，P < 。01，P < 。05）和荟萃分析（分别为P < . 001，P < . 05）。维生素 B12 缺乏与高同型半胱氨酸血症相结合是 EPL 更严重的危险因素（优势比 = 4.98，P = 0.002）。因此，我们得出结论，维生素 B12 缺乏和同型半胱氨酸水平升高是 EPL 的独立危险因素，并且当两者结合时具有更高的风险。维生素 B12 和同型半胱氨酸水平的评估可作为 EPL 风险的良好筛查标志。