The gist: drinking, smoking, taking prescription meds or failing to eat a balanced diet can influence the health of men’s future children. This is a comprehensive article by Emily Anthes (from 2010 but still way ahead of conventional wisdom) that goes into the science of how a dad’s behavior can impact his wife’s pregnancy and the health/mental health of his developing child. Anthes begins with animal testing but gets right into the latest on humans. Highly recommended read!
While Robaire was slogging away (on mice experiments), other scientists were quietly accumulating similar evidence. Some of the early work showed that women had more miscarriages when their male partners worked in manufacturing jobs where they were exposed to heavy metals, such as lead and mercury. Men exposed to pesticides were more likely to have children who developed leukemia. (For years, studies have linked Agent Orange, an herbicide used during the Vietnam War, to birth defects in the offspring of veterans, but a causal link has not been definitively established.) Other research suggested that men who worked with solvents, cleaning solutions, dyes and textiles, paints and other chemicals were all more likely to father kids with birth defects or childhood cancers.
Scientists also showed that it didn’t require industrial-strength chemicals to wreak havoc on men’s sperm. Smokers seemed to produce sperm with the wrong number of chromosomes, a DNA error that could lead to miscarriages or Down syndrome. (A stunning 2008 paper revealed that men with deficiencies in folate, that superstar maternal vitamin, had the same problem.) Paternal smoking has also been linked to childhood cancer, and even alcohol and caffeine can cause sperm abnormalities that derail child development.
We now know that what started as an inconceivable mystery — how could men’s environments and lifestyles possibly affect the children they would later father? — has not just one but several answers. Certain substances interfere with the earliest phase of sperm production in the testes, prompting errors in cell division that lead to genetic mutations in immature sperm cells. Chemicals can also cause what are known as epigenetic mutations, which don’t change the DNA sequence itself but alter how the body reads these genetic instructions. Essentially, an epigenetic change involves turning certain genes on or off, telling the body to pay more or less attention to the code they contain. (If genetic changes are akin to changing the lyrics of a song, epigenetic changes are like fiddling with the volume.)
Drugs can also interfere with sperm transport. A 2009 study revealed that a standard dose of paroxetine — the active drug in the antidepressant marketed as Paxil — causes a fivefold increase in the number of men who show evidence of “sperm fragmentation,” which can increase the chances of miscarriage. Researchers have known that certain antidepressants can influence ejaculatory response; it turns out that they seem to slow the transportation of sperm through the male reproductive system, causing the cells to age prematurely. “Sperm are being damaged because they’re not traveling properly through the body,” says Peter Schlegel, who led the study and is a urologist at New York’s Weill Cornell Medical College.
And these findings are just the beginning. Consider, for instance, that there are some 84,000 chemicals used in American workplaces, says Barbara Grajewski, a senior epidemiologist at the National Institute of Occupational Safety and Health. Only 4,000 of these have even been evaluated for reproductive effects in men or women, and males are particularly understudied. “There’s a whole range of effects in men that really are not being given attention or are well understood,” Grajewski says. “The whole area of men’s reproductive health is way behind women’s health.”
The implications of this research deficit are huge. Some 60 percent of all birth defects today are of unknown origin; tracing even a small fraction of these back to men’s environmental exposures would constitute a major public health advance.
Despite the accumulating findings, the idea that fathers can somehow contribute to birth defects has gained little traction in the public sphere. Cigarette packs have no warnings about the association between male smokers and birth defects. A woman who drinks while she’s pregnant can be prosecuted, but most men have no idea that drinking in the months before conception is risky.
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