Table 4 Association between pubertal timing and menstrual characteristics and endometriosis (N = 940)

Age group at thelarche (year)

 Normal thelarche (11–13)

Ref.

Ref.

 Early thelarche (≤10)

1.00(0.47, 2.11)

1.13(0.52, 2.45)

0.756

 Late thelarche (≥ 14)

2.29(0.51, 10.27)

2.39(0.50, 11.54)

0.276

Age group at menarche (year)

 Normal menarche (12–15)

Ref.

Ref.

 Early menarche (< 12)

1.69(0.63, 4.50)

1.75(0.63, 4.90)

0.284

 Late menarche (≥ 16)

3.32(1.31, 8.42)

2.59(0.93, 7.22)

0.068

Ever diagnosed with precocious puberty

 No

Ref.

Ref.

 Yes

1.00(0.23, 4.26)

1.00(0.22, 4.58)

0.996

Regular menstrual cycle in the past 12 months

0.000

0.094

 No

Ref.

Ref.

 Yes

1.06(0.54, 2.07)

0.95(0.47, 1.91)

0.889

Regular menstrual periods in the past 12 months

 No

Ref.

Ref.

 Yes

0.96(0.48, 1.91)

0.96(0.46, 1.96)

0.901

Menstrual quantity in the past 12 months (amount of bleeding)

 Little

Ref.

Ref.

 Moderate

1.41(0.52, 3.84)

1.65(0.59, 4.57)

0.338

 Heavy

3.63(1.16, 11.39)

4.92(1.50, 16.15)

0.009

 Heavy with large clots

6.59(1.81, 24.05)

5.67(1.42, 22.56)

0.014

Menstrual flow length in the past 12 months (days)

 < 3

Ref.

Ref.

 3–7

1.00(0.23, 4.27)

0.95(0.21, 4.29)

0.946

 > 7

–

–

–