Dental X-Rays Tied to Low Birth Weight
Experts Say Danger Occurs Before a Woman Knows She's Pregnant
Damage Done in Skull?
Still, even the American Dental Association recommends that pregnant women avoid elective dental X-rays until after delivery. "And when dentists must give X-rays to pregnant women, they usually have them wear two lead shields to protect the fetus," says Hujoel.
He notes that his study is now the third to show a possible connection between low birth-weight babies and low-dose radiation. And one of the theories is that the danger comes from radiation exposure to the woman's thyroid, pituitary, or hypothalamus glands -- rather than radiation directly to the fetus or woman's reproductive organs. These glands produce the hormones necessary for pregnancy and normal fetal development. In his current study, Hujoel looked at thyroid radiation exposure rather than radiation exposure to the fetus and the woman's reproductive organs.
"Our research was a population study and didn't examine the possible cause-and-effect, but the damage from dental X-rays may be in the skull," he tells WebMD. "That's why our findings suggest that this is something we should take a closer look at."
When his study was conducted from 1993 to 2000, very few pregnant women getting dental X-rays wore lead "thyroid shields" that protect the neck -- and thyroid -- from radiation. Now, thyroid shields are routinely used, and in fact, recommended by the ADA for all patients "whenever possible" in addition to traditional abdominal shielding with lead aprons.
Avoidance Is Best
Two other experts not involved in Hujoel's study call his findings "interesting" and agree that it warrants further study. For now, both say women who even suspect they may be pregnant should avoid dental X-rays.
"The impact of this paper is that it makes you stop and think, we should probably study this more closely, but I don't think women should be hysterically upset by this finding," says Laura Riley, MD, assistant professor of obstetrics and gynecology at Harvard Medical School and a spokeswoman for the American College of Obstetricians and Gynecologists.
"We generally advise women not to get dental X-rays during pregnancy unless there's an imperative reason for them -- and there usually isn't," she tells WebMD. "What is much more common, and what I suspect is the reason for the association in this study, is that people go to the dentist for regular care and get an X-ray before they know they are pregnant."
This view was echoed by Diane Ashton, MD, associate medical director of the March of Dimes. "We always recommend that whenever possible, pregnant women should avoid X-ray radiation," she says. "And this study points to the importance of women visiting their dentists before becoming pregnant."