What Does Dad’s Job Have to Do with Baby’s Birth Defects?

A study draws some unexpected links between a father's job — mathematician, for example, along with office workers and artists — and a greater likelihood of birth defects in his offspring

Dads who work as architects, dentists, firefighters, fishermen, car assembly workers or painters may have chosen wisely, at least according to a new study finding that these professions aren’t linked to an increased risk of birth defects in men’s offspring. The study, by researchers at the North Carolina Center for Birth  Defects Research and Prevention, found that certain jobs held by expectant fathers appeared to be associated with varying likelihoods of birth defects in their babies. In many cases, the connections seemed counterintuitive: ostensibly innocuous professions including mathematicians, office workers and artists fell into the increased risk category, while jobs that would appear to carry greater risk — painters who regularly inhale fumes, for example — did not.

The study did not examine whether occupational exposures were responsible for the heightened risk of birth defects, but the authors theorize that they may play a role. Tania Desrosiers, one of the study’s authors, said that factors contributing to birth defects may not always be obvious. “It could be, for example, that exposure to video display terminals among computer scientists is relevant, or that sitting all day at a desk raises scrotal temperature and causes damage to the sperm,” Desrosiers wrote in an email. “We can only hypothesize about the underlying mechanisms.”

The study, published in Occupational and Environmental Medicine, relied on data from the U.S. National Birth Defects Prevention Study, which is exploring a wide range of potential risk factors for major birth defects. Researchers looked at the job histories of about 5,000 fathers — nearly 1,000 dads who had a child with one or more congenital abnormalities born between 1997 and 2004 and more than 4,000 dads whose kids did not have birth defects.

The researchers also sorted jobs into 63 groups according to their exposure to chemicals or other potential dangers. Only those jobs held by fathers in the three months leading up to conception and during the first month of pregnancy were included; 90% of the dads had just one job during these four months, which are considered the time period when aberrations are most likely to be transmitted in sperm. Complex mathematical analyses revealed that the following job types appeared to be connected with a greater chance of having a child with a birth defect in at least three categories:

•      mathematicians, physicists and computer scientists

•      artists

•      photographers and photo processors

•      food service workers

•      landscapers and groundsmen

•      hairdressers and make-up artists

•      office and admin support workers

•      sawmill operatives

•      those working with petrol and gas

•      those working in chemical industries

•      printers

•      those operating cranes and diggers

•      drivers

Some job fields were more likely to be associated with specific defects in babies: artists, for example, were more likely to have babies with defects of the mouth, eyes and ears, gut, limbs and heart. Photographers and photo processors were more likely to have babies with cataracts, glaucoma or defective eye tissue, while landscapers were more prone to having babies with gut abnormalities.

About a third of the 63 job groups were not associated with increased risk for birth defects. These categories included: architects and designers; health-care professionals; dentists; firefighters; fishermen; car assembly workers; entertainers; smelters and foundry workers; stonemasons and glass blowers/cutters; painters; train drivers/maintenance engineers; soldiers; commercial divers.

The findings are provocative and may serve as a jumping-off point for deeper research, but it’s important to note that the current results are no reason for men to engage in sudden resume-buffing. Said Desrosiers: “…While we observed increases in risk of birth defects among children of fathers with different types of jobs, the occurrence of birth defects in the general population is rare. We don’t advise that dads-to-be change jobs, though it may be prudent to reduce or avoid unnecessary exposure to potentially toxic exposures at work.”

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