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.
Journal of Clinical Endocrinology and Metabolism, 2014, Vol 99, Issue 6, p. 2241-2249
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; 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  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; Journal Article; Research Support, Non-U.S. Gov't