The Controversy Over Thyroid Screening for All Pregnant Women

The issue of whether or not to screen all pregnant women for thyroid problems with a thyroid stimulating hormone (TSH) test is controversial. According to the 2011 Guidelines of the American Thyroid Association (ATA) for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum, there is evidence that between 2% to 3% of pregnant women will have elevated TSH levels at the time of routine screening.

Some studies have found that undiagnosed and untreated thyroid problems - including overt hyperthyroidism, overt hypothyroidism and subclinical hypothyroidism - are linked to maternal and fetal problems. But the research is mixed, and there is no agreement about treatment.

The ATA guidelines did say that treatment of thyroid dysfunction (as defined as a TSH above 2.5 mIU/L in women who were positive for thyroid peroxidase antibodies) was associated with a significantly lower risk of various complications, including:

• miscarriage
• hypertension
• preeclampsia
• gestational diabetes
• placental abruption
• cesarean delivery
• congestive heart failure
• preterm delivery

While the evidence for or against the medical benefits or cost-effectiveness of universal TSH screening during the first trimester visit is insufficient, the guidelines did recommend that women who are at higher risk for thyroid dysfunction may benefit from thyroid screening. Those at high risk for thyroid disease during pregnancy include women:

• with a personal history of thyroid dysfunction and/or thyroid surgery
• with a family history of thyroid disease
• with a goiter
• with thyroid antibodies
• with symptoms or clinical signs that may suggest hypothyroidism
• with type I diabetes
• with a history of either miscarriage or preterm delivery
• with other autoimmune disorders that are often linked to autoimmune thyroid problems, such as: vitiligo, adrenal insufficiency, hypoparathyroidism, atrophic gastritis, pernicious anemia, systemic sclerosis, systemic lupus erythematosus and Sjogren's syndrome
• with infertility
• who have previously received radiation to the head or neck area as a cancer treatment, or who have had multiple dental x-rays
• who are morbidly obese, which is defined as a body mass index (BMI) of over 40, or a body weight that is 20% or more over ideal body weight
• who are age 30 or older
• who have been treated with amiodarone (Cordarone) for heart rhythm irregularities
• who have been treated with lithium
• who, in the previous six weeks, have been exposed to iodine in a medical test contrast agent

Any pregnant woman who has concerns about thyroid function, or who has has thyroid risk factors should talk to her physician about the best course of action to protect her health and the health of her baby.

Important Note

A study reported on at the 2012 Endocrine Society conference -- Endo 2012 -- reported that even mild thyroid dysfunction -- which would not otherwise be diagnosed as "hypothyroidism" -- greatly increases the risk of serious problems. In particular, women who had mild dysfunction had -- compared to pregnant women with normal thyroid function --

• double the risk of miscarriage, premature labor, and low birth weight
• seven times greater risk of stillbirth

According to the study's lead author, Jubbin Jagan Jacob, MD: "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."

_Sources:

_{Stagnaro-Green, Alex, et. al. "Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum." Thyroid. Volume 21, Number 10, 2011 (Online)}

_{Endocrine Society - Endo 2012 Press Release, June 2012}