Marmor D, Izard V, Schahmaneche D, Benoît G, Jardin A
Unité de Médecine de la Reproduction, Hôpital Saint-Antoine, Paris.
Presse Med. 1998 Oct 3;27(29):1484-90.
In 1992, a statistical analysis of data from 61 studies of semen quality among normal men led to the conclusion that human sperm count fell of 40% from 1940 to 1990. This meta-analysis has since been invalidated for methodological reasons as well as for statistical reasons, but it caused enormous concern to both the scientific community and to the international media. A decline of human fertility was speculated. To date, the most popular hypothesis offered to explain this alleged decline has been increasing exposure to environmental estrogen mimicking chemicals. However, there is no evidence that male or mammal fertility is declining. Moreover, the sperm count of breeding mammals did not declined in the meanwhile. Since 1992, numerous papers reported on men investigated during the last 20 years have shown conflicting results, from sperm count improvement to sperm count decline. However, several publications included methodological and analytical biases. In fact, the techniques used for semen analysis have to be questioned. It is a subjective exam, lacking laboratory standards and quality control procedures. This induces very important variations between laboratories and between biologists. For the sperm count itself, numerous errors can occur, provoked by the technique, the equipment and the reader: for the same sperm, the coefficient of variation can exceed 40% between two technicians. Therefore, the current techniques of semen analysis cannot warrant epidemiological studies. It is indispensable to admit the limits of the semen analysis in order to improve as much as possible its quality and its reliability.
1992年，一项对61项关于正常男性精液质量研究的数据进行的统计分析得出结论：从1940年到1990年，人类精子数量下降了40%。此后，这项荟萃分析因方法学原因以及统计原因而失效，但它引起了科学界和国际媒体的极大关注。人们猜测人类生育能力在下降。迄今为止，为解释这种所谓下降而提出的最流行假说是，接触环境中类似雌激素的化学物质增多。然而，没有证据表明男性或哺乳动物的生育能力在下降。此外，与此同时，繁殖期哺乳动物的精子数量并未下降。自1992年以来，众多关于过去20年中接受调查男性的论文呈现出相互矛盾的结果，从精子数量增加到精子数量下降。然而，一些出版物存在方法学和分析偏差。事实上，用于精液分析的技术值得质疑。这是一项主观检查，缺乏实验室标准和质量控制程序。这导致不同实验室以及不同生物学家之间存在非常大的差异。对于精子数量本身，由于技术、设备和操作人员的原因可能会出现许多误差：对于同一个精子样本，两名技术人员检测结果的变异系数可能超过40%。因此，当前的精液分析技术无法保证流行病学研究的准确性。必须承认精液分析的局限性，以便尽可能提高其质量和可靠性。
