Table 1: Age and age-standardized characteristics of study participants by self-reported hypothyroidism and hyperthyroidism at the midpoints (1992 for Nurses’ Health Study (NHS) and 1999 for NHSII) of the follow-up periods (NHS: 1976–2010 and NHSII: 1989–2011).

NHSNHSII
No thyroid dysfunctionHypothyroidismHyperthyroidismNo thyroid dysfunctionHypothyroidismHyperthyroidism

Percentage of person-time*93.26.20.691.67.80.6
Number764694534388882017634622
Age, mean (SD), years58.1 (7.2)59.4 (7.0)57.5 (7.1)43.8 (4.6)44.9 (4.6)44.2 (4.6)
Body mass index, mean (SD), kg/m226.0 (5.0)27.4 (5.6)26.1 (4.8)26.3 (6.1)28.3 (7.0)26.0 (6.0)
≥30 pack-years of cigarette smoking, %19.416.226.82.62.54.8
History of hypertension, %30.736.139.212.918.013.0
History of diabetes, %5.07.56.62.04.62.3
Parity, mean (SD), number of children2.9 (1.7)2.9 (1.6)2.9 (1.6)1.8 (1.2)1.8 (1.2)1.8 (1.2)
Oral contraceptive use duration, mean (SD), years2.0 (3.4)2.0 (3.4)2.2 (3.5)4.7 (4.8)4.4 (4.5)4.7 (4.9)
Age at menarche, mean (SD), years12.6 (1.4)12.5 (1.5)12.5 (1.3)12.4 (1.4)12.3 (1.5)12.4 (1.5)
Current estrogen only postmenopausal hormone use (5+ years), % 4.29.25.30.40.81.5
Age at menopause, mean (SD), years49.7 (3.7)49.7 (3.8)49.6 (3.6)46.3 (4.2)46.0 (4.8)46.1 (4.0)
Age at last birth, mean (SD), years∣∣31.4 (4.4)31.1 (4.2)31.3 (4.4)30.9 (4.7)30.7 (4.8)31.2 (4.7)
Tubal ligation, %16.917.814.819.520.720.7
History of infertility, %11.214.112.619.121.424.2
Family history of breast or ovarian cancer, %12.713.212.410.110.510.1
Family history of uterine cancer, %2.62.72.72.52.84.1

Over entire followup (1976–2010 in NHS and 1989–2011 in NHSII).
Among postmenopausal women.
Among women with natural menopause.
Among parous women.