Study Suggests Long-Term Decline in French Sperm Quality

New study findings suggest widespread declines in sperm quality in French men between 1989 and 2005, with average sperm counts falling while percentages of abnormally formed sperm rose. These findings are a “serious public health warning,” the authors wrote, although they point out the average estimated sperm count is still well above the level deemed normal by the World Health Organization. Recent years have seen many similar reports of falling human sperm counts, but there has been much debate over whether the problem is real. “The principal trouble has been selection bias,” says Joëlle Le Moal, an environmental health epidemiologist at the Institut de Veille Sanitaire in Saint Maurice, France, and joint first author of the new article with colleague Matthieu Rolland. She explains that few studies have involved sperm samples collected from randomly selected members of the general population; for the few that did, only a small percentage of men agreed to be included, and the studies were run in restricted areas. So most studies have had to rely on sperm donors or couples coming to fertility clinics, which do not represent the general population. However, although this study population also involved couples attending fertility clinics, the men were partners of women known to be totally infertile—their fallopian tubes were either missing or blocked. So the men were not recruited on the basis of their own infertility. “[This] is why we argue that they can be considered a close reflection of the general male population,” Le Moal says. Using Fécondation in Vitro National (FIVNAT), France’s registry of fertility clinic data, the researchers identified 26,609 male partners of women attending 126 clinics all over France between 1989 and 2005. The study relied on data from each couple’s first attempt at assisted reproduction, during which the men, aged 18–70, provided fresh ejaculate. Data on the sperm concentration, morphology, and motility for each sample were extracted for statistical analysis. The investigators computed mean sperm data for each year and adjusted the means to represent an average 35-year-old man. The men’s average age increased from 34.2 to 35.9 over the 17-year study period. During that time the investigators saw an average 32.2% reduction in mean sperm concentration—an average of 1.9% per year—and the projected concentration for a 35-year-old man fell from an average 73.6 million/mL to an average