Neonatal outcomes associated with maternal treatment for Graves’ disease

Abstract

Background : Both the status of maternal Graves’ disease and the methods of treatment can cause a variety of impacts on their fetuses and newborn infants.

Objective : To determine the clinical outcome and thyroid function test (TFT) of the infants born to the women who have been diagnosed with Graves’ disease.

Methods : The study was performed on the infants born to mothers with Graves’ disease at King Chulalongkorn Memorial Hospital between April 1999 and March 2006. They were examined and tested for serum FT 4 or T 4 and TSH levels at age > 48 hours (screening tests). Infants suspected of thyroid disease would have repeated serum FT 4 and TSH test within 1 - 2 weeks. Tc99 thyroid scan was performed if congenital hypothyroidism was suspected. The infants were divided into 3 groups according to the methods of treatment their mothers had previously received. Group 1, 2, 3 were defined for maternal treatment with anti-thyroid drug, I 131 and surgery, respectively. Comparison of clinical outcomes and TFT among these 3 groups of infants were performed.

Results : One hundred and ninety pregnant women delivered 191 infants were enrolled. There were 131, 49 and 11 infants in group 1, 2 and 3, respectively. During pregnancy, 91 women were on propyl thiouracil (PTU), 47 on L-thyroxine and 52 were not on medication. There were more percentage of women in Group 1 who received PTU (64.6%, 12.2% and 9.1% respectively) and fewer of them (5.4%, 69.4% and 54.5% respectively) needed L-thyroxine. Among these infants, there was no statistical difference in terms of mean maternal age, gestational age, birth weight and proportion of small-for-gestational-age infants. Congenital anomalies were found in 5 infants (2.6%). Thyroid dysfunction was found in 15 infants (7.8%). Five were found with congenital hypothyroidism, 1 transient hypothyroidism, 2 fetal hyperthyroidism, 1 symptomatic hyperthyroidism and 6 asymptomatic hyperthyroidism. Screening levels of TSH and FT 4 of infants, whose mothers were taking PTU during pregnancy, were significantly higher and lower than the others (p < 0.001, ANOVA test). The maximum dosage of maternal PTU were also correlated significantly with the level of screening TSH (r = 0.44, p< 0.001) and screening FT 4 (r = -0.47, p < 0.001) of the infants (Pearson Correlation).

Conclusion : Infants born to Graves’ disease mothers are at risk of congenital anomalies and thyroid dysfunction. Careful physical examination and thyroid function test should be closely monitored in these infants.