The kids of custodians and chemists may be at greater risk for some birth defects than children of parents with other occupations, researchers say.
In a survey of mothers of children with birth defects, those who were janitors or scientists were more likely to have children with certain conditions, Michele Herdt-Losavio of the New York State Department of Health and colleagues reported online in the journal Occupational and Environmental Medicine.
Herdt-Losavio said her team didn't assess what factors may account for this association but offered a possible explanation.
"What we can guess by looking at these job titles is that ... it's possible that they work with chemicals," she said. "It's not possible to say what those chemicals might be, or how much they might work with. But what we can do is point other [researchers] in the direction and give them some idea of where they might want to dig further and collect more data."
Herdt-Losavio said she and her colleagues are currently looking further into the "scientist" category -- which encompassed biological scientists, chemists, pharmacists, engineers, and geologists -- to determine which fields may be most at risk.
The team conducted the study because several previous efforts had found an association between a mother's occupation and a child's birth defects. Most, however, have grouped birth defects together, without assessing individual problems.
So they looked at 45 specific birth defects among 24 different maternal occupations. They analyzed 8,977 cases of birth defects and 3,833 healthy controls from the National Birth Defects Prevention Study and conducted telephone interviews with mothers.
What they found was that women working as janitors had a significantly increased risk of giving birth to a child who had one or more of seven specific defects: ear and eye defects, musculoskeletal and gastrointestinal problems, and oral clefts, among others, Herdt-Losavio said.
Janitorial occupations had previously been associated with neural tube defects, spina bifida, and oral clefts, the researchers said.
Women working as scientists had an increased risk of five defects -- notably heart defects, as well as musculoskeletal defects and one gastrointestinal defect.
Electronic equipment operators also were more likely to give birth to children with defects.
Herdt-Losavio said one of the "more interesting" groups in the study was teachers, because they had a reduced risk of giving birth to children with defects -- particularly gastroschisis, neural tube defects, spina bifida, and septal heart defects.
Healthcare workers had reduced risks of three specific defects, but they also had an increased risk for two defects.
Herdt-Losavio noted that the paper is meant to be a starting point for more research, and that future work should look at specific groups in more detail to better understand the associations.
"Our hope with this study was to do a broad spectrum of these defects, which in most cases we tried to be very specific with and take into account a large number of occupations, so that other researchers can have an idea where future studies should be looking," she said.