Skip to main content

Table 1 Distribution of risk factors in different ages at first childbirth

From: Age at first childbirth and breast cancer survival: a prospective cohort study

FactorNullipara (n = 83)< 20 years (n = 114)21 to ≤ 25 years (n = 252)26 to ≤ 30 years (n = 188)> 30 years (n = 74)Missing (n = 54)
Age at baseline, year (765)
Mean (SD)
57.3 (7.7)55.5 (6.3)56.5 (7.1)57.2 (7.1)56.8 (7.9)57.1 (5.3)
Socioeconomical status (720)
 Manual worker26.54939.425.726.411.1
 Nonmanual worker68.74755.368.465.383.3
 Employer-self-employed4.845.35.98.35.6
 Body mass index (765)
Mean (SD)
25.6 (4.1)26.6 (4.1)25.5 (4.1)25.1 (3.4)25.6 (4.2)23.9 (3.2)
Alcohol consumption (765)
 Nothing last year8.411.410.710.19.50
 Something last year (not last month)9.613.210.76.916.21.3
 Something last month81.974.678.28374.394.4
Smoking (765)
 Never50.635.140.951.643.233.3
 Current26.531.630.620.225.738.9
 Ex22.933.328.628.231.127.8
Age at menarche (722)
 ≤ 1221.726.32414.221.616.7
 > 12 to < 154753.548.45956.850
 ≥ 1531.320.227.626.821.633.3
Age at menopause (714)
 Pre/perimenopausal31.738.93832.234.227.8
 ≤ 4512.214.212.28.213.716.7
 > 45 to < 5343.934.533.946.432.944.4
 ≥ 5312.212.415.913.119.211.1
Parity (711)
 Nullipara10000000
 1019.311.12563.50
 2038.658.75835.1
 3027.224.214.91.40
 ≥ 4014.962.100
  1. Column percent (mean and SD in italics)