Falling sperm qualityBMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6947.131b (Published 09 July 1994) Cite this as: BMJ 1994;309:131
- Niels Keiding,
- Aleksander Giwercman,
- Elisabeth Carlsen,
- Niels E Skakkebaek
- Professor Statistical Research Unit, University of Copenhagen, Panun Institute, DK-2200 Copenhagen, Denmark Senior registrar Research fellow Professor University Department of Growth and Reproduction, Section GR-5064, Rigshospitalet, DK-2100 Copenhagen, Denmark.
EDITOR,—Stephen Farrow comments on the quality of the evidence concerning a possible decline in sperm quality,1 focusing attention on our paper published in 1992.2 Farrow also responds to a paper by Peter Bromwich and colleagues, for which we provided the commentary.3
Farrow questions our systematic search of the databases MEDLINE and Index Medicus. A necessary requirement for a valid overview, however, is that the criteria for including articles in the overview (and for excluding them) are explicit and reproducible to avoid selection bias. Several precautions were taken to avoid any undue influence of papers with small numbers of men in them. …