Table 2 Reproductive data reported at baseline for all women and women with and without incident fracture

Age at menarche

17,189

n (%)

n (%)

< 0.001

  < 11

(years)

826 (7.2)

335 (5.9)

 12–15

(years)

9731 (84.4)

4774 (84.3)

  > 16

(years)

968 (8.4)

555 (9.8)

Age at menopause

12,468

0.029

  < 40

(years)

358 (4.5)

172 (3.8)

 40–44

(years)

776 (9.8)

443 (9.8)

 45–54

(years)

6085 (76.6)

3438 (76.0)

  > 55

(years)

723 (9.1)

473 (10.5)

Number of born children

17,028

0.01

 no children

1466 (12.8)

756 (13.5)

 1–2 children

7347 (64.2)

3455 (61.8)

  ≥ 3 children

2628 (23.0)

1376 (24.6)

Total duration of lactation

18,326

 no lactation

(months)

3202 (26.0)

1623 (26.9)

0.002

 1–6

(months)

3918 (31.8)

1752 (29.1)

 7–18

(months)

4180 (34.0)

2149 (35.7)

  ≥ 19

(months)

1003 (8.2)

499 (8.3)

Age at first delivery

14,794

0.007

  ≤ 19

(years)

1295 (13.0)

542 (11.2)

 20–34

(years)

8318 (83.5)

4121 (85.4)

  ≥ 35

(years)

354 (3.6)

164 (3.4)

Ever use of menopausal hormone therapy

7441

(yes)

1336 (26.4)

663 (27.8)

0.229

Hysterectomy and/or salpingoophorectomy

7457

(yes)

769 (15.2)

396 (16.6)

0.125

Miscarriages > 3

3892

(yes)

249 (9.5)

139 (10.9)

0.157

Ever use of oral contraceptives

17,306

(yes)

6049 (49.2)

2441 (40.5)

< 0.001

Total use of oral contraceptives

8206

0.027

  < 10

(years)

3676 (62.8)

1525 (64.9)

 11–19

(years)

1162 (19.8)

471 (20.1)

  > 20

(years)

1020 (17.4)

352 (15.0)

median (Q2-Q4^b)

median (Q2-Q4^b)

Start use of oral contraceptives at age

8323

(age)

25.0 (21.0–31.0)

27.0 (22.0–34.0)

< 0.001

Reproductive period

12,398

(years)

36.0 (33.0–39.0)

36.0 (33.0–39.0)

0.088

Total use of menopausal hormone therapy

1763

(years)

3.0 (2.0–6.0)

3.0 (2.0–7.8)

0.004