Testing the Thyroid During Pregnancy

Hypothyroidism in first trimester of pregnancy can lead to birth complications

(RxWiki News) In the midst of all the tests and check-ups that women undergo during their pregnancies, women may want to ensure that their thyroid is tested early in pregnancy, or even before they become pregnant.

An unpublished study being presented at a conference has found that a thyroid gland that's even moderately dysfunctional may be linked to complications during birth for pregnant women.

"Ask your OB/GYN about thyroid testing."

Jubbin Jagan Jacob, MD, an associate professor at Christian Medical College and Hospital in Punjab, India, led the study to determine what effects an improperly working thyroid gland might have on women's pregnancies.

The thyroid gland in your neck produces hormones which help regulate your body's process of converting food into energy. If the gland does not produce enough of these hormones or isn't responsive to specific hormonal signals from the brain, it causes a condition called hypothyroidism.

The symptoms of hypothyroidism include fatigue, constipation, depression and feeling especially sensitive to cold temperatures.

A pregnant woman with hypothyroidism is at risk for complications such as miscarriage, stillbirth, having a baby with a very low birthweight or other problems.

Dr. Jacob and colleagues measured the thyroid levels of 1,000 pregnant women during the first trimester and studied the 796 women who had a normal (533 women) or only a mildly dysfunctional thyroid (263 women).

The team followed the women until they gave birth and tracked the rates of miscarriage, stillbirth, premature labor, low birth weight and several other birth complications.

They found that women with a thyroid gland that was moderately dysfunctional were still seven times more likely than the women with normal thyroids to have a stillbirth, and they were twice as likely to have a miscarriage before the 20th week of pregnancy or to have a premature and/or underweight baby at birth.

"These findings add to the now increasing evidence from previous studies that all pregnant women, irrespective of their risk for thyroid problems, probably should be screened for thyroid dysfunction within the first three months of getting pregnant," Dr. Jacob said.

Andrea Campaigne, MD, of Nurture OBGYN in Austin, Texas, told dailyRx that thyroid disease is common among women during childbearing ages and can go undetected. She also said that women who have not recently been screened should consider getting screened because of the risks during pregnancy.

However, she pointed out that women and their doctors should be cautious about interpreting the results from thyroid screenings, which involve assessing a woman's symptoms and measuring the amount of thyroid-stimulating-hormone, or TSH, present in her body.

"The common symptoms of the first trimester of pregnancy are also common symptoms of hypothyroidism," Dr. Campaigne said. "This should not prevent a woman from getting screening, but it may confuse her or her physician's interpretation of her hormone/metabolic balance."

In addition, she said that the pregnancy hormone human chorionic gonadotropin (hCG) can interact with TSH, and hCG is especially active during the first trimester when most thyroid screenings would occur.

"This also means that vigilance should be used in following up an abnormal result as we frequently see women's need for thyroid medications wax and wane in and around reproductive events," Dr. Campaigne said. An abnormal result could also be subclinical hypothyroidism, which means a thyroid gland that may be just starting to act improperly before outside symptoms are evident.

A different, possibly preferable course of action, said Dr. Campaigne, is to be screened before pregnancy, especially since an abnormal thyroid can affect fertility problems as well.

"Perhaps a better strategy is to recommend universal screening and appreciation for a healthy, tuned-up approach to thyroid health pre-pregnancy and not once the impact may have already been made on the first trimester fetus," she said.

The study was presented June 23 at The Endocrine Society's 94th Annual Meeting in Houston. Because the study has not yet been published in a peer-reviewed journal, its results should be regarded as preliminary and still require review by researchers in the field. The study was funded by Christian Medical College and Hospital. No information on disclosures was available.

Review Date: 
June 29, 2012