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Development of Autoimmune Overt Hypothyroidism Is Highly Associated With Live Births and Induced Abortions but Only in Premenopausal Women

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Abstract

Context: The 1-year postpartum period is often accompanied by increased risk for thyroid disease. Objective: The objective of the study was to investigate the role of reproductive risk factors in the development of autoimmune overt hypothyroidism in the years after the 1-year postpartum period. Design, Setting, and Subjects: In a population study, we included Danish women with new autoimmune overt hypothyroidism not diagnosed within the first year after a pregnancy (n = 117; median age 53.0 y) and age-andregion-matched euthyroid controls from the same population (n = 468). Main Outcome Measures: In conditional multivariate logistic regression models, we analyzed the associations between the development of autoimmune hypothyroidism and age at menarche/menopause, years of menstruations, pregnancies, spontaneous and induced abortions, live births, and years on oral contraceptives and postmenopausal hormone replacement therapy, also taking various possible confounders into account. Results: In multivariate regression models with no event as reference, the odds ratios (ORs) for hypothyroidism [95% confidence interval (CI)] after one/two/three or more live births were 1.72 (0.56-5.32)/3.12 (1.14-8.48)/4.51 (1.65-12.3) and 1.02 (0.57-1.81)/2.70 (1.27-5.75) after one/two or more induced abortions. Findings were valid only for women having hypothyroidism diagnosed before the age of 55 years. We found no association between disease development and other reproductive risk factors investigated. Conclusions: Previous live births and induced abortions were major risk factors for the development of autoimmune overt hypothyroidism in women aged up to 55 years. The increased risk for hypothyroidism after giving birth extends longer than just to the 1-year postpartum period, and numbers of previous pregnancies should be taken into account when evaluating the risk of hypothyroidism in a young women.

ENDOCRINOLOGY SYSTEMIC-LUPUS-ERYTHEMATOSUS THYROID-DISEASE RISK-FACTORS THYROGLOBULIN AUTOANTIBODIES RHEUMATOID-ARTHRITIS REPRODUCTIVE FACTORS ORAL-CONTRACEPTIVES FEMALE RELATIVES IODINE INTAKE POPULATION menopause menstruation postpartum period pregnancy premenopausal autoimmune overt hypothyroidism immune system disease endocrine disease/thyroid etiology spontaneous abortion Abortion Spontaneous (MeSH) reproductive system disease/female complications Primates Mammalia Vertebrata Chordata Animalia (Animals Chordates Humans Mammals Primates Vertebrates) - Hominidae [86215] human common adolescent aged middle age adult female Danish oral contraceptive drug contraceptive-drug 12512 Pathology - Therapy 16506 Reproductive system - Pathology 17002 Endocrine - General 17018 Endocrine - Thyroid 22005 Pharmacology - Clinical pharmacology 22028 Pharmacology - Reproductive system and implantation studies 24500 Gerontology 25000 Pediatrics 34508 Immunology - Immunopathology tissue immunology Human Medicine Medical Sciences induced abortion therapeutic and prophylactic techniques clinical techniques multivariate logistic regression model mathematical and computer techniques postmenopausal hormone replacement therapy therapeutic and prophylactic techniques clinical techniques Clinical Endocrinology Clinical Immunology Gynecology Abortion Induced Adolescent Adult Aged Case-Control Studies Cross-Sectional Studies Denmark Female Hashimoto Disease Humans Infant Newborn Live Birth Middle Aged Pregnancy Premenopause Risk Factors Young Adult