British Fertility Rate Has Improved Since

A research study in the June 3 issue of the British medical journal The Lancet should go a long way toward reassuring those who believe environmental pollution or other factors are adversely affecting reproductive health.

Michael Joffe, a physician in the Department of Epidemiology and Public Health of the Imperial College of Medicine, London, analyzed the interval from time of initiating unprotected intercourse to successful conception in a group of randomly selected British couples. This time period was termed time to pregnancy, or TTP, and was used as a measure of fertility — the shorter the TTP, the higher the fertility rate. Joffe stated that his theory was that a suspected pollution-induced decline in “semen quality” might be responsible for a presumed decline in fertility in Britain.

The results of his study indicated the exact opposite, however. The trend for fertility, as measured by the TTP, was steadily upward for the study period — 1961 to 1993. Analyzing TTP in over 1,500 British parents, he discovered that between 1961 and 1965, 79 percent of couples conceived a child within one year of trying; in the interval between 1991 to 1993, that figure had risen to 90 percent. The equivalent success rates for conception within 6 months were 65 percent 40 years ago, and 80 percent more recently.

These results held up despite several adjustments for other variables, such as maternal age and smoking.

The study findings directly refuted Joffe’s initial belief that some environmental factor or factors were causing a diminution in men’s ability to father children. These findings lend further support to those of a group of California physicians, who reported in March that there had been no decline in sperm counts or quality between 1951 and 1997 in men seeking treatment for infertility at the University of Southern California clinic.

Joffe concludes that if “chemical agents are relevant [to fertility], either there has been no adverse impact on male fertility during this period, or any such effect has been more than compensated by a countervailing increase in couple fertility.”

In the same issue of The Lancet, an editorial co-authored by E R te Velde and two colleagues from Utrecht University Medical Center, Netherlands, discusses the complexities of measuring biological fertility. They comment that Joffe’s study shows “that at present the near-panic sometimes expressed in the lay press about the effects of environmental pollution on sperm quality and male fertility is not justified.”

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