Thyroid Research Thyroid Research Archive Hyperthyroidism

Heart failure in pregnant women with hyperthyroidism is usually precipitated by a disorder of pregnancy

(March 2004)

The background of the study. There are similar changes in the function of the heart and vascular system in normal pregnant women and patients with hyperthyroidism, including a decrease in vascular resistance and an increase in heart rate and cardiac output. Occasionally, the heart cannot adapt to the changes, and heart failure ensues. This study was done to determine the factors associated with heart failure in pregnant women with hyperthyroidism.

How the study was done. Among slightly more than 300,000 women who delivered babies at the Parkland Hospital in Dallas, Texas, 150 (<0.05 percent) had hyperthyroidism during their pregnancy. Thirteen (9 percent) of the 150 women had heart failure. They ranged in age from 17 to 34 years, and the duration of pregnancy ranged from 18 to 37 weeks.

The results of the study. Six women had heart failure before the time of fetal viability (23 weeks). Three of them had an incomplete abortion, uterine hemorrhage, and severe infection, and two had severe infections. Only one of the six women had no complicating problems.

Seven women had been pregnant for 29 or more weeks. Four were known to have hyperthyroidism, but were not taking prescribed therapy, and three had received no prenatal care. Four of these women had severe preeclampsia or eclampsia, three had anemia, two had infections, and one had no complicating problems.

All the women responded rapidly to treatment for heart failure, hyperthyroidism, and any complicating problems. Eleven of the women were evaluated 2 or more years later, and all had normal heart function.

The conclusions of the study. Most pregnant women with hyperthyroidism who have heart failure also have an infection or complications of pregnancy.

The original article. Sheffield JS, Cunningham FG. Thyrotoxicosis and heart failure that complicate pregnancy. Am J Obstet Gynecol 2004;190:211-7.