Characteristics (N = 1,114 case-control pairs) | Case* | Control | P^{†} |
---|---|---|---|

Age (y) | 56.7 (9.1) | 56.7 (9.1) | |

Height (cm) | 162.3 (6.6) | 162.3 (6.7) | 0.97 |

Weight (kg) | 65.7 (11.5) | 65.6 (11.3) | 0.81 |

BMI | 25.0 (4.2) | 24.9 (4.2) | 0.91 |

Age at menarche (y) | 12.9 (1.5) | 13.0 (1.5) | 0.05 |

n = 1,084 | n = 1,090 | ||

Age at first birth (y) | 24.8 (4.7) | 24.3 (4.4) | 0.05 |

n = 932 | n = 981 | ||

Parity (% parous) | 84.2 | 88.4 | 0.004 |

Number of live births | 2.5 (1.8) | 2.7 (1.8) | <0.001 |

n = 1,113 | |||

Postmenopausal (%) | 74.7 | 76.0 | 0.46 |

Natural menopause | 42.6 | 45.0 | |

Surgical menopause | 32.1 | 31.1 | |

Age at menopause (y)^{‡} | 50.99 (50.94-51.04) | 50.92 (50.85-50.99) | 0.03 |

n = 992 | n = 998 | ||

Hormone replacement therapy (% ever use) | 35.7 | 32.5 | 0.11 |

Years of hormone replacement therapy use | 2.4 (5.6) | 2.1 (5.4) | 0.07 |

n = 1,096 | n = 1,092 | ||

Breast cancer in first degree relative (%) | <0.001 | ||

0 | 79.4 | 84.4 | |

1 | 18.0 | 14.4 | |

2+ | 2.6 | 1.3 | |

Percent density | 32.7 (19.7) | 26.9 (19.1) | <0.001 |

↵* Data shown is mean (SD) for continuous variables (except age at menopause), percentage for categorical variables.

↵†

*P*values for age at menopause is based on log-rank test, for symmetrically distributed variable is based on paired*t*test, for nonsymmetrically distributed variable is based on Wilcoxon rank sum test, and for categorical variable is based on Mantel-Haenszel χ^{2}test. All statistical tests are two-sided.↵‡ Median age at menopause and 95% CI from Kaplan-Meier estimates.