Table 2 Some baseline characteristics according to reproductive and hormonal variables
Mean age at recruitment, years (SD)Mean BMI (SD)Percentage in upper 1/3 socioeconomic group (n)
Parity:
Nulliparous56.0 (4.8)25.8 (4.9)33.9 (47 551)
156.0 (4.8)26.1 (4.7)32.7 (59 749)
255.6 (4.8)26.0 (4.5)37.4 (203 355)
356.3 (4.6)26.5 (4.7)31.9 (89 159)
4 or more57.2 (4.7)27.4 (5.2)21.6 (31 774)
Age at menarche, years:
⩽1155.5 (4.5)27.5 (5.2)32.6 (84 577)
1255.8 (4.6)26.5 (4.7)35.3 (79 412)
1356.0 (4.7)26.0 (4.5)35.5 (109 593)
1456.3 (4.7)25.7 (4.4)32.9 (85 785)
15+56.7 (4.7)25.5 (4.4)30.2 (65 055)
Menopausal status:*
Pre/peri50.9 (1.4)26.2 (5.0)36.9 (49 391)
Post52.1 (1.5)26.1 (4.9)32.8 (35 279)
Age at menopause, years:†
⩽4859.4 (3.7)26.3 (4.8)28.6 (30 401)
49–5158.8 (3.9)26.3 (4.7)32.4 (34 209)
52+59.2 (3.6)26.7 (4.8)34.5 (43 696)
OC use:
Never57.8 (4.6)26.5 (4.8)32.0 (165 145)
Ever54.8 (4.3)26.0 (4.6)34.5 (263 942)
HRT use:‡
Never26.5 (4.9)26.5 (4.9)32.1 (157 892)
Past26.5 (4.6)26.5 (4.6)33.8 (61 106)
Current25.7 (4.3)25.7 (5.0)35.3 (116 928)
  • *In 243 523 women aged <55 years at recruitment who never used HRT. †In 350 586 postmenopausal women (with a natural menopause) who never used HRT and were aged over 52 years at recruitment. ‡In postmenopausal women in categories based on last reported use of HRT (see Methods).

  • BMI, body mass index; HRT, hormone replacement therapy; OC, oral contraceptive.