Table 4 Associations between BBD with and without considering parity and timing of first birth relative to BBD diagnosis and changes in mammographic breast density (percent MBD, dense area, non-dense area), EDMD

 BBD

67

−0.21

0.46

0.65

− 1.10, 0.69

− 0.08

0.47

0.86

− 1.00, 0.84

 No BBD

330

Ref

–

–

–

Ref

–

–

–

 No BBD, nulliparous

68

−0.40

0.39

0.30

−1.16, 0.36

−0.27

0.39

0.48

− 1.03, 0.49

 No BBD, parous

262

Ref

–

–

–

Ref

–

–

–

 BBD, nulliparous

15

−0.13

1.06

0.90

−2.20, 1.94

0.01

1.07

0.99

−2.09, 2.11

 BBD before first birth

19

0.71

0.57

0.22

−0.41, 1.83

1.03

0.59

0.08

−0.12, 2.18

 BBD after first birth

31

−1.01

0.67

0.13

−2.32, 0.29

−0.95

0.68

0.16

−2.28, 0.38

 BBD

67

−0.46

0.63

0.47

−1.70, 0.78

−0.33

0.63

0.61

−1.57, 0.91

 No BBD

330

Ref

–

–

–

Ref

–

–

–

 No BBD, nulliparous

68

−0.21

0.46

0.65

−1.10, 0.69

−0.13

0.45

0.77

−1.01, 0.75

 No BBD, parous

262

Ref

–

–

–

Ref

–

–

–

 BBD, nulliparous

15

−0.33

1.32

0.80

−2.92, 2.25

−0.07

1.34

0.96

−2.70, 2.57

 BBD before first birth

19

0.38

0.61

0.53

−0.82, 1.58

0.48

0.56

0.39

−0.62, 1.58

 BBD after first birth

31

−1.45

1.05

0.17

−3.51, 0.60

−1.30

1.06

0.22

−3.37, 0.77

 BBD

67

1.94

0.95

0.04

0.08, 3.80

1.71

1.02

0.09

−0.29, 3.71

 No BBD

330

Ref

–

–

–

Ref

–

–

–

 No BBD, nulliparous

68

1.08

1.15

0.35

−1.17, 3.33

0.92

1.09

0.40

−1.23, 3.07

 No BBD, parous

262

Ref

–

–

–

Ref

–

–

–

 BBD, nulliparous

15

2.21

2.00

0.27

−1.72, 6.13

1.83

2.09

0.38

−2.27, 5.93

 BBD before first birth

19

−0.29

0.69

0.68

−1.64, 1.06

− 0.68

0.68

0.31

−2.01, 0.65

 BBD after first birth

31

3.48

1.59

0.03

0.37, 6.59

3.43

1.71

0.05

0.08, 6.79