不妊症は増えていない　

1999/5/25　ロイター　最近の報告では男性の精子数減少により不妊症が多くなっていると推測されているが、20歳以上のスウェーデン女性全員の検討によると逆に減少傾向であった。研究者は不妊症に影響する淋病の激減が不妊症減少に関係していると信じている。

No evidence of rise in infertility

NEW YORK, May 25 (Reuters Health) -- A study of Swedish women finds no evidence to support recent claims of a global rise in infertility.
In fact, ``the proportion of subfertile women (in Sweden) decreased from 12.7% in 1983 to 8.3% in 1993,'' according to researchers led by Dr. Olof Akre of the Karolinska Institute in Stockholm. Their findings are published in the June issue of the journal Fertility and Sterility.
Recent reports have suggested that a possible decline in semen quality around the world might trigger an overall decline in fertility. However, according to the Swedish research team ''collective evidence of decreasing human fertility... is (currently) not available.''
To study fertility trends, the researchers examined rates of subfertility (difficulties in conceiving) among all Swedish women over 20 years of age who bore their first child between 1983-1993.
They found that rates of subfertility actually declined by more than 4% over those 10 years. As expected, older women were at higher risk for subfertility compared with younger women -- women over 40 years of age were at 4 times the risk of subfertility than women in their early 20s, according to the investigators.
Akre and colleagues credit the rise in fertility rates on ''the virtual eradication'' of gonorrhea -- a cause of female infertility -- over the past 30 years. ``Between 1970 and 1992, the incidence of diagnosed gonorrhea in women dropped from over 2,000 per 100,000 population per year to 3 per 100,000 population per year,'' they point out.
The authors were unable to determine the role, if any, of male infertility in the observed changes in fertility rates. However, they speculate that ``if a decrease in male fertility is present, it is both minor and outweighed by other determinants of total fertility.''
SOURCE: Fertility and Sterility 1999;71:1066-1069.