男女出生率 接近平衡是自然规律，但昨日广州军区总医院放射科主任欧陕兴告诉记者，统计表明城市中女孩出生率要远高于男孩，而农村仍保持平衡 或相反。“尽管目前仍无权威结论说明这一现象，但压力、辐射降低Y精子存活 率的可能性很大。”
欧陕兴举了个切身例子：“在医院放射科工作的医生大多生女儿；从事媒体行业的，比如电视台的记者，长期被仪器射线辐射，生女儿 的也比较多。
“如果觉得这只是个案，那么某婚恋网站的调查能从侧面说明问题。”欧陕兴表示，一项针对部分一、二线城市 男女比例 的调查显示，加入择偶市场的男女比惊人地达到3比7。
为何城里人生女多？欧陕兴称，尽管目前科学上无权威结论说明这一问题，但压力、辐射降低Y精子存活率的可能性非常大。“城里人，工作压力 大，生活环境 差，受到的辐射也比农村多得多，生女儿的可能性很大。”
他建议各位准父母 注意身心健康 ，在调整心态 舒缓压力 的同时，尽量减少接触射线的机会。“否则不是生儿生女 的问题，变成能不能生的问题了。”
为何城市女孩出生率高于男孩？
压力、辐射降低Y精子存活率的可能性非常大。“城里人，工作压力大，生活环境差，受到的辐射也比农村多得多，生女儿的可能性很大。”因为你有重男轻女的思想
解密：美国、日本男孩出生率为何下降？
解密：美国、日本男孩出生率为何下降？Male births declining in the US and Japan
Male births declining in US and Japan
Mother Nature has always ensured that male births outnumber female ones, but the gap has been gradually narrowing over the past three decades in the U.S. and Japan, according to a new study.
Researchers suspect the decline in male births can be explained, at least in part, by paternal exposure to environmental toxins, such as certain pesticides, heavy metals, solvents or dioxins -- chemical byproducts produced during incineration or the manufacture of other chemicals.
Traditionally, it's been expected that for every 100 girls born, there will be about 105 boys. But since 1970, the U.S. and Japan have experienced a downward shift in this male-to-female birth ratio, researchers report in the online edition of the journal Environmental Health Perspectives.
In the U.S., the proportion of boys dropped from 105.5 per 100 girls in 1970 to 104.6 in 2001; in Japan, the male-to-female ratio dropped from 106.3 boys for every 100 girls to just fewer than 105 per 100.
The changes may seem small, but the study authors suspect they are one manifestation of the effects of environmental pollutants on the male reproductive system.
The decline in male births has occurred "at the same time that we've been seeing other signs that male reproductive health is in danger," said lead study author Dr. Devra Lee Davis, a professor of epidemiology at the University of Pittsburgh Graduate School of Public Health.
These other signs, she said, include lower testosterone levels and sperm counts, as well as increases in testicular cancer, a disease that most often affects young men.
Environmental toxins may be a common denominator here, according to Davis and her colleagues. Such exposures may specifically lower rates of male, rather than female, births for a few reasons. They may, for example, affect the viability of sperm that bear the Y chromosome, which determines male sex -- or the viability of male fetuses.
Davis's team found that while fetal deaths have declined overall in recent decades, the proportion of male deaths is growing. In Japan, in particular, male fetuses accounted for about two thirds of all fetal deaths in the 1990s.
Over the years, there have been a number of reports showing that heavy exposure to certain pollutants may affect a man's likelihood of fathering a son.
从人类的自然发展史来看，男孩的出生数量总是多于女孩，但据一项最新调查显示，美国和日本的男女出生数量差距在过去三十年中逐渐缩小。
评论