Variables studied

Girls already sexually active

OR [95% CI]

p-value

Yes

(n = 649)

No

(n = 330)

1. Sibling size

­ ≤ 3

66 (10.2)

44 (13.3)

0.74 [0.49 - 1.11]

0.13840

­ 4 - 7

286 (44.1)

154 (46.7))

0.90 [0.69 - 1.17]

0.43968

­ 8 - 11

209 (32.2)

88 (26.7)

1.31 [0.97 - 1.75]

0.07485

­ 12 - 15

75 (11.6)

43 (13.0)

0.87 [0.58 - 1.30]

0.50308

­ ≥16

13 (2.0)

1 (0.03)

6.72 [0.87 - 51.63]

0.03418

M ± ET

7.4 ± 3.2

6.6 ± 3.3

0.50 [0.21 - 1.17]

Extreme

1 et 18

1 et 14

2. Sibling rank

­ ≤ 3rd

407 (62.7)

209 (63.3)

0.97 [0.74 - 1.28]

0.84907

­ 4 - 7th

165 (25.4)

77 (23.4)

1.12 [0.82 - 1.53]

0.47354

­ ≥8th

77 (11.9)

44 (13.3)

0.88 [0.59 - 1.30]

0.50917

M ± ET

3.5 ± 2.5

3.8 ± 2.9

KW = 1.7498

0.1859

Extreme

1 et 10

1 et 13

2. Menarche age

­ 10 - 11

31 (4.8)

32 (9.7)

0.47 [0.28 - 0.78]

0.00302

­ 12 - 13

231 (35.6)

165 (50.0)

0.55 [0.42 - 0.72]

0.00001

­ 14 - 15

319 (49.2)

99 (30.0)

2.26 [1.70 - 2.99]

0.00000

­ 16 - 17

68 (10.5)

34 (10.3)

1.02 [0.66 - 1.57]

0.93262

M ± ET

13.7 ± 1.4

13.4 ± 1.5

F = 5.5777

0.0184

Extreme

11 et 17

11 et 17