Table 4 Association between parental ages at birth and risk of breast cancer in daughters after stratified by menopause status

Premenopause

Paternal age

Mean ± SD

33.7 ± 7.0

32.9 ± 6.6

1.16 (0.98–1.38)^†

<30

183 (31.6)

210 (36.3)

1.0

1.0

30–34

162 (28.0)

161 (27.8)

1.1 (0.85–1.54)

1.1 (0.76–1.50)

35–39

108 (18.7)

105 (18.1)

1.1 (0.82–1.60)

1.2 (0.77–1.85)

≥40

126 (21.8)

103 (17.8)

1.4 (1.00–1.93)

1.9 (1.12–3.26)

P for trend

0.062

0.031

Maternal age

Mean ± SD

29.1 ± 5.8

28.8 ± 6.1

1.06 (0.87–1.29)^†

<25

133 (23.0)

159 (27.5)

1.0

1.0

25–29

194 (33.5)

187 (32.3)

1.3 (0.93–1.73)

1.2 (0.86–1.70)

30–34

147 (25.4)

120 (20.7)

1.5 (1.06–2.07)

1.2 (0.78–1.88)

≥35

105 (18.1)

113 (19.5)

1.1 (0.76–1.55)

0.7 (0.38–1.15)

P for trend

0.363

0.361

Postmenopause

Paternal age

Mean ± SD

32.2 ± 8.1

31.8 ± 8.0

1.11 (0.94–1.32)^†

<30

179 (41.4)

190 (44.0)

1.0

1.0

30–34

104 (24.1)

100 (23.2)

1.2 (0.82–1.65)

1.0 (0.66–1.48)

35–39

61 (14.1)

69 (16.0)

1.0 (0.65–1.49)

0.8 (0.47–1.35)

≥40

88 (20.4)

73 (16.9)

1.4 (0.94–2.03)

1.2 (0.66–2.29)

P for trend

0.173

0.804

Maternal age

Mean ± SD

28.2 ± 7.1

27.7 ± 6.9

1.16 (0.95–1.41)^†

<25

152 (35.2)

171 (39.6)

1.0

1.0

25–29

108 (25.0)

110 (25.5)

1.1 (0.80–1.60)

1.2 (0.80–2.29)

30–34

90 (20.8)

72 (16.7)

1.6 (1.05–2.31)

1.6 (0.97–2.69)

≥35

82 (19.0)

79 (18.3)

1.2 (0.82–1.78)

1.1 (0.58–2.03)

P for trend

0.112

0.415