Previous live births and induced abortions were demonstrated to be risk factors for the development of autoimmune hypothyroidism, with a heightened risk for disease extending beyond the 1-year postpartum period.
Study findings published in The Journal of Clinical Endocrinology & Metabolism showed that the number of previous pregnancies and abortions should be taken into account during a clinical evaluation of hypothyroidism in women younger than 55 years.
Researchers in Denmark constructed a population study that included data on women with new autoimmune overt hypothyroid diagnoses (n=117; median age, 53 years). These disease cases were not diagnosed within the first year after pregnancy. Data from participants in the study group was compared with that of age- and region-matched euthyroid controls.
“Pregnancy is associated with various modulations of the immune system that may influence the risk for development of autoimmune disorders,” the researchers wrote.
According to the study, previous research has linked pregnancy to a reduced risk for some autoimmune disorders, such as Graves’ disease.
“On the other hand, the risk of autoimmune disease after delivery and after abortion may be even higher than it was before pregnancy,” researchers said.
Statistical analysis showed that the ORs for hypothyroidism were increased after the first birth and higher after each subsequent birth (after one birth, OR=1.72; 95% CI, 0.56-5.32; after two, OR=3.12; 95% CI, 1.14-8.48; and after three or more live births, OR=4.51; 95% CI, 1.64-12.3).
ORs for hypothyroidism also were increased after a first abortion (OR=1.02; 95% CI, 0.57-1.81), and subsequently higher after two or more abortions (OR=2.7; 95% CI, 1.27-5.75).
The study findings were valid only for women younger than 55 years, which may render the data significant for premenopausal women who seek an explanation for hypothyroid symptoms.
Disclosure: The researchers report no relevant financial disclosures.