Baby Boys on the Decline; Pollution May Be Factor

May 28, 2008 02:50 PM
by Cara McDonough
Some believe fewer boy births are the result of natural population swings, but others think pollution and stress are to blame.

30-Second Summary

The ratio of baby boys to girls has been declining in the United States since 1970, with 17 fewer males for every 10,000 births, according to a study last year in the journal Environmental Health Perspectives.

Now, scientists are looking for causes.

Some experts say the shift is part of a natural, cyclical population pattern. But new research suggests that exposure to pollutants such as pesticides, mercury and lead may be damaging male fetuses, causing miscarriage, or affecting men’s testosterone levels, which play a role in determining a baby’s sex, causing fewer boys to be conceived.

Another emerging theory is that stress can damage Y-bearing sperm, reducing the chance of a boy being conceived.

But can environmental factors really affect the sex of a baby?

In April, a British study suggesting that a mother’s diet determines her baby’s sex raised skepticism as well as ethical concerns.

Although many theories abound, there is “relatively little a couple can do” to alter the chances of having a boy or a girl, writes Rob Shmerling for Harvard Health.

“If you have a strong preference for a boy or a girl, your options are limited. You could plan to have enough babies so both genders are eventually represented. Or it may be better to rethink your position and hope for a healthy baby of either sex,” he writes.

Headline Links: ‘A Puzzle Over Fewer Boy Births’

Background: Baby boys on the decline

Related Topics: Affecting and choosing a baby’s sex

Opinion & Analysis: The facts and the myths, and the strength of females

Reference: Pregnancy


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