OBJECTIVE To investigate the impact of serum vitamin D level on in vitro fertilization (IVF) outcomes. DESIGN Systematic review and meta-analysis. SETTING Not applicable. PATIENTS Infertile women undergoing conventional IVF or intracytoplasmic sperm injection (ICSI). INTERVENTIONS Systematic search of PubMed, MEDLINE, EMBASE, Global Health, The Cochrane Library, Health Technology Assessment Database, and Web of Science from inception until July 2019 with cross-checking of references from relevant articles in English. Vitamin D levels were categorized into three groups: deficient (<20 ng/mL), insufficient (20-30 ng/mL), and replete (>30 ng/mL). Before starting the data extraction, we registered the review protocol in PROSPERO (CRD42019134258). MAIN OUTCOME MEASURES We consider clinical pregnancy rate (CPR), live birth rate (LBR), and/or ongoing pregnancy rate (OPR) as primary outcomes. Likewise, the miscarriage rate was considered as a secondary outcome. RESULTS Primary analysis showed that women with a replete level of vitamin D had higher CPR and LBR/OPR compared to those with a deficient of insufficient level of vitamin D. However, sensitivity analysis led to non-significant differences between the comparators for CPR (odds ratio 0.71, 95% confidence interval 0.47-1.08, I2 = 61%) and OPR/LBR (odds ratio 0.78, 95% confidence interval 0.56-1.08], I2 = 61%). Also, for miscarriage a statistically different rate was not reached. CONCLUSION Serum vitamin D levels do not influence IVF outcomes in terms of CPR, LBR/OPR, and miscarriage rate. Future large cohort studies are warranted to determine whether the threshold of vitamin D affects reproductive outcomes. Currently, there is a lack of consensus between the appropriate vitamin D threshold to predict reproductive outcomes compared to the one established for bone health. PROSPERO NUMBER CRD42019134258.

中文翻译：

---

维生素 D 水平如何影响体外受精结果：系统评价和荟萃分析的结果

目的 研究血清维生素 D 水平对体外受精 (IVF) 结果的影响。设计系统评价和荟萃分析。设置 不适用。患者 接受常规试管婴儿或卵胞浆内单精子注射 (ICSI) 的不孕妇女。干预 系统搜索 PubMed、MEDLINE、EMBASE、Global Health、Cochrane 图书馆、卫生技术评估数据库和科学网，从开始到 2019 年 7 月，并交叉检查相关英文文章的参考文献。维生素 D 水平分为三组：缺乏（<20 ng/mL）、不足（20-30 ng/mL）和充足（>30 ng/mL）。在开始数据提取之前，我们在 PROSPERO (CRD42019134258) 中注册了审查协议。主要结局指标我们考虑临床妊娠率 (CPR)、活产率 (LBR)、和/或持续妊娠率 (OPR) 作为主要结果。同样，流产率被视为次要结果。结果 初步分析显示，与维生素 D 水平不足的女性相比，维生素 D 水平充足的女性具有更高的 CPR 和 LBR/OPR。然而，敏感性分析导致 CPR 比较者之间的非显着差异（几率比率 0.71，95% 置信区间 0.47-1.08，I2 = 61%）和 OPR/LBR（优势比 0.78，95% 置信区间 0.56-1.08]，I2 = 61%）。此外，未达到流产统计上的不同比率。结论 血清维生素 D 水平不会影响体外受精结果，如 CPR、LBR/OPR 和流产率。未来的大型队列研究有必要确定维生素 D 的阈值是否影响生殖结果。现在，与为骨骼健康建立的阈值相比，预测生殖结果的适当维生素 D 阈值之间缺乏共识。繁荣号 CRD42019134258。