WASHINGTON, Jan. 17 (UPI) -- Women who have thyroid disease may be more likely to have babies with birth defects, according to a Johns Hopkins study that the author and thyroid experts said Thursday was preliminary but which could lead to more routine testing.
Dr. David Nagey, co-author and professor of gynecology and obstetrics at Johns Hopkins in Baltimore, Md., said in a telephone interview, "It's important what we did gets confirmed by somebody else." He added while the findings from the retrospective study are important, they should not cause a major change in behavior but would imply "women with (a history) of thyroid disease prior to pregnancy see a thyroid specialist" and be monitored through pregnancy.
The study, which Nagey presented Thursday at the annual meeting of the Society for Maternal-Fetal Medicine in New Orleans, said women with thyroid disease were at higher risk of giving birth to infants with heart, brain and kidney defects, even if thyroid tests were normal during the pregnancy.
Babies born to women with either overactive or underactive thyroids also were at increased risk of having a cleft lip or palate or extra fingers. Women with underactive thyroid had babies at increased risk for cardiac problems, even if the mother was on thyroid medication during pregnancy.
The study included 101 women with either hypothyroidism -- underactive thyroids -- or hyperthyroidism -- the overactive type. The women had an average age of 31 and all gave birth at birth at Johns Hopkins Hospital from 1994 to 1999.
Of the resulting 108 pregnancies and 114 fetuses among the women, 21 babies -- 18 percent -- had birth defects. Among a subgroup of 86 women who had a thyroid test during the first trimester of pregnancy, 17 babies or 20 percent had birth defects. Women with underactive thyroids had a higher risk of have a baby with a medical problem than did women with overactive thyroids.
Nagey said there already was evidence of an increased risk -- mostly intellectual or developmental problems -- in children as a result of underactive thyroid pregnancies, but the link with birth defects was new.
Nagey said it is possible the same antibodies that cause the underactive thyroid also could be responsible for the birth defects.
"It's a very, very important study and I would urge more research in the area and strongly urge all women to get a thyroid test when they think they might be pregnant," Dr. Lawrence Wood, of Massachusetts General Hospital and president of the Thyroid Federation International told United Press International.
He called for additional studies to replicate the findings and questioned the average age of the women included in the Hopkins research, adding 31 was possibly older than the average pregnant woman. Age itself plays a factor in the risk of birth defects.
Dr. Alex Stagnaro-Green, dean for curriculum and academic affiliation at Mount Sinai School of Medicine in New York and an expert on thyroid disease and pregnancy, said this study comes amid an explosion of information about how thyroid disease affects pregnant women and babies, including a recent study that suggested it resulted in decreased IQ.
Despite the attention, he said, there still are no definitive recommendations from the various medical associations on thyroid testing of pregnant women.
He said a weakness in the study was that it was retrospective, which introduces a bias in the candidate selection process and leaves out key clues about the women's total health picture, such as why they received thyroid testing and whether they had other medical problems that might cause birth defects in their babies.
"All that being said, they are pretty interesting data," Green said. "I'm intrigued by it, but I think it's preliminary."
He said while additional studies need to be done, prospective studies and studies done with better control groups, the data "impacts somewhat my thinking on whether we should screen all women, but it doesn't give me a definitive answer."
