Dr. Jubbin Jagan Jacob of Christian Medical College and Hospital, Ludhiana, India, and colleagues found even moderate thyroid dysfunction during early pregnancy significantly increases the risk of serious complications.
Thyroid hormone, produced by the thyroid gland, helps regulate the process of turning food into energy, but excessively low hormone production, or hypothyroidism, may cause symptoms such as fatigue, sensitivity to cold temperatures, constipation and depression.
However, during pregnancy untreated, hypothyroidism is associated with an increased risk of miscarriage, stillbirth, low birth weight and other serious complications. Although previous research has suggested that women with moderate thyroid dysfunction, or subclinical hypothyroidism, also are more likely to suffer complications, the level of risk was uncertain.
The study found even mild thyroid dysfunction that did not meet the criteria for hypothyroidism greatly increased the risk of serious problems -- compared to pregnant women with normal thyroid function, the risk was doubled for miscarriage, premature labor, low birth weight and seven times greater for still birth.
The finding were presented at The Endocrine Society's 94th annual meeting in Houston.