09/24/2004

Fathers' Occupational Exposures May be Linked to Birth Defects

Can exposure to hazardous substances at work contribute to the development of
birth defects? If so, then fathers' occupational exposures may play a more
important role than mothers' exposures, suggests a study in the September
Journal of Occupational and Environmental Medicine, official publication of the
American College of Occupational and Environmental Medicine (ACOEM).

Led by Dr. Sin-Eng Chia of National University of Singapore, the researchers
looked at whether rates of common birth defects were related to parents'
occupations. The study included data on all babies born in Singapore from 1994
through 1998 -- nearly 238,000 infants.

Links between occupational categories and birth defects were much more common
for the fathers' jobs than for the mothers'. For example, babies whose fathers
were clerical workers were 2.25 times more likely to be born with heart
defects, compared to those who worked as senior officers and managers.

The risk of heart defects was also approximately doubled for babies of fathers
classified as production craftsmen. The same job category was also linked to a
nearly tripled risk of a group of relatively minor congenital musculoskeletal
deformities.

One fathers' job category -- plant and machine operators and assemblers -- was
linked to all three of the most common birth defect categories. Associations
included a 2.5 times increase in heart defects, a tripled risk of
musculoskeletal defects and more than a fivefold increase in risk of defects
involving the urinary system.

For mothers' occupations, just one significant relationship was found. The risk
of urinary system defects was about 3.5 times higher for babies whose mothers
were classified as professionals.

In Singapore, as in other developing countries, more and more women are working
outside the home, including during pregnancy. This makes it important to
understand how possible exposure to hazardous conditions at work might affect
the risk of birth defects.

However, the new results suggest that fathers' exposures are more strongly
related to birth defects than the mothers' exposures are. The risks may be
highest for fathers working as plant and machine operators, compared with those
working at the senior or managerial level.

More research is needed to clarify the true meaning of the results. For
example, the links between occupational groups and birth defects may reflect
social and economic factors, rather than exposure to hazardous substances.


The study finds no specific exposures linked to specific birth defects, but it
does highlight the potential importance of fathers' occupational exposures.
"Future studies of pregnancy outcomes should not ignore the father," Dr. Chia
and colleagues conclude.

Further Information


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