Increased Risk of Graves' Disease After Pregnancy

Abstract

The improvement in autoimmune thyroid disease during pregnancy and the subsequent exacerbation postpartum is secondary to immune system changes necessary to a normal pregnancy. Prior studies have shown that a clinically significant number of women develop Graves' disease (GD) in the postpartum period. The aim of this study was to examine the risk of post pregnancy GD and define patient characteristics that may impact the diagnosis and treatment strategies for this group. We performed a retrospective review of 152 consecutive women, aged 18-39 years when diagnosed with GD, to examine the relation between disease diagnosis and prior pregnancy. Differences in patient characteristics and treatment outcomes of women were analyzed. New York City population data were used to estimate a relative risk for the development of postpartum GD. We found that in parous women, 45% were diagnosed with GD in the postpartum period and 55% had an onset in subsequent years. No significant differences were noted in patient characteristics or treatment outcomes. We found that the risk of women developing post pregnancy GD was greatest in the older patients (35-39 years), with 56% developing GD compared to 42% of nulliparous women. These data, therefore, suggest an increased risk for older women. We were able to calculate the increase in estimated relative risk for postpartum disease by using control population data. The risk maximized at 5.6 for the age group 35-39 years when compared to the control population. These data support earlier studies that showed that a clinically significant number of women develop GD after childbirth compared to nulliparous women and extends this risk for many years. The mechanism of this long-standing increased susceptibility requires further delineation.