Findings from several high profile meta-analyses have raised concerns about an ongoing global decline in sperm concentration and male fertility. However, these studies exhibit considerable heterogeneity in key variables including study population, methodology, fertility status, and geographic region.

中文翻译：

---

有生育能力的美国男性精子浓度保持稳定：系统评价和荟萃分析


几项备受瞩目的荟萃分析的结果引发了人们对全球精子浓度和男性生育能力持续下降的担忧。然而，这些研究在关键变量上表现出相当大的异质性，包括研究人群、方法、生育状况和地理区域。