Thyroid disorders during pregnancy are a leading cause of premature birth and miscarriages, yet doctors say pregnant women around the world are rarely screened for thyroid abnormalities. From VOA's New York Bureau, we have the story by Amanda Cassandra.
The thyroid is a butterfly shaped gland at the base of the neck, which secretes hormones containing iodide that regulate the speed at which the cells in the body work. If too much of the thyroid hormone is produced, the body cells work faster than normal and the thyroid is overactive, which is hyperthyroidism.
However, if too few of the hormones are produced, the body cells work more slowly, the thyroid is underactive and hypothyroidism occurs.
Dr. Alex Stagnaro-Green, a professor of Obstetrics and Gynecology at New Jersey Medical School, says thyroid disease is, after diabetes, the most common endocrine disease worldwide during pregnancy, due in large part to iodide deficiency.
"Iodide deficiency is probably the number one problem when it comes to thyroid disease worldwide, in many of the countries both in Europe and in the developing world," said Dr. Stagnaro-Green. "And it is probably the number one reason why children are born with decreased I.Q. What really is needed in those countries is some form of intervention that all mothers who are pregnant get iodide before pregnancy and during pregnancy."
Iodide deficiency usually happens when soil contains low levels of iodine, causing a low concentration of iodine in food products and insufficient iodine intake in the population.
According to the World Health Organization, the number of countries where iodine deficiency is a public health problem was reduced to 54 in 2003, down from 110 in 1993 through its program of salt iodization. The WHO says the drop is due mainly to the use of iodized salt for human and animal consumption to prevent and control iodine deficiency.
Dr. Stagnaro-Green says during pregnancy, a baby's development is dependent on the mother's thyroid function. If thyroid abnormalities are not detected, he says it can lead to several complications for mother and baby.
"The first is that in the first and second trimesters, women who have an underactive thyroid, those women [have] an increased chance of miscarriage," he said. "The second way it [works] is that women who are hyperthyroid in the third trimester are very prone to pre-term delivery prior to 37 weeks. And those are the infants that have a high death rate and also have a lot of congenital abnormalities. Unfortunately, it doesn't stop there, it continues in the post partum period. Studies have shown that if the mother has slight abnormalities in her thyroid hormone in the first or second trimester, it can have a deleterious impact on the unborn child in regards to the I.Q. five to 10 years later."
Dr. Stagnaro-Green says women need to be educated about the symptoms of thyroid disease because they can easily be overlooked.
"All of those thyroid hormonal changes that occur in the first year, are often ascribed to the mother being tired, dealing with a newborn, but in fact many of them are really due to the hormonal changes that are occurring and are not being diagnosed," continued Dr. Stagnaro-Green.
Despite the risk of a higher rate of miscarriages and premature births, Dr. Stagnaro-Green says physicians have been reluctant to require testing for the disease as a regular part of the prenatal care.
"One of the most exciting studies that has come out in the last 30 years was published this year, about six month ago, from a group in Italy," he said. "Half the women they gave thyroid hormone, the other half they didn't give thyroid hormone. They found that the half they gave thyroid hormone to, their miscarriage rate and their preterm delivery rate was at the normal level. The half that had thyroid antibodies and not given the thyroid hormone, their miscarriage rate was four to eight times higher. That was the first study that's demonstrated that an intervention makes a difference. If another study confirms that and expands upon it, then there will probably be a very strong call for universal screening for all women for thyroid disease in pregnancy."
Dr. Stagnaro-Green says because hormonal levels fluctuate during pregnancy, it is important to monitor thyroid abnormalities.
He says although there is not yet a mandate from the global medical community to test women for the disease, women with a history of thyroid disease or a history of miscarriage or premature birth should be screened.