U.S. sperm trend conclusions.

The letter written by Heinze (1) has serious shortcomings. Heinze wrote that There is not a single study of healthy men from any fertility center or sperm bank that has reported a decline in sperm counts in the United States. This is not true. A number of such studies exist. Leto and Frensilli (2) documented a decline in sperm counts in potential sperm donors from all over the United States in a longitudinal study. Heinze stated that A study by MacLeod and Wang (3) indicates that sperm counts have remained constant in New York since 1938. That study was dated 1979 and was on men ascertained at a fertility center. Although their sperm counts were stable over the years preceding 1979, it does not necessarily follow that sperm counts of fertile men were stable too. Male fertility potential in terms of semen quality: a review of the past, a study of the There is not a single [confirmed] study of healthy men from any fertility center or sperm bank that has reported a decline in sperm counts in the United States. The study of Leto and Frensilli (2) is contradicted by the four longitudinal studies cited in my letter, which report no decline in sperm counts in five regions of the United States over periods ranging from 10 to 30 years (1). Earlier data on trends in sperm counts were reviewed by MacLeod and Wang (3), who concluded that enough data have been presented to indicate that there has not been a substantial change in the numerical aspect of semen quality. Saidi et al. (4), in a recently published review of 29 U.S. studies from the late 1930s to the late 1990s, found "no significant changes in sperm counts during the last 60 years." MacLeod and Wang (3) reviewed all of the U.S. data available up to that time (1979), including data from fertile men as well as from men evaluated at a fertility center. The earliest data on sperm counts in New York City, published in 1938 (5), were on prenatal couples (i.e., men of known fertility); mean counts (137 x 106/mL) from this study are virtually identical to the mean counts (131.5 x 106/mL) reported in the most recent study from New York City published in 1996 (6), which focused on donors to sperm banks Male fertility potential in terms of semen quality: a review of the past, …