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Table 1 Basic characteristic of participants by birth cohort (n = 301,744)

From: Breastfeeding duration of different age groups and its associated factors among Chinese women: a cross-sectional study

  1930–1938 (n = 26,723) 1939–1948 (n = 57,571) 1949–1958 (n = 99,680) 1959–1968 (n = 92,452) 1969–1974 (n = 25,318)
Mean age/years, (SD) 70.5 (2.4) 61.6 (3.1) 52.0 (3.0) 41.8 (2.9) 35.7 (1.4)
Rural residency, % 43.6 53.3 55.5 58.8 60.1
Urban residency, % 56.5 46.7 44.5 41.2 40.0
Highest education, %
 Primary school 85.9 75.0 63.4 34.7 38.5
 Middle school 6.8 14.8 21.7 38.2 36.7
 High school and above 7.3 10.3 14.8 27.1 24.7
Household size, %
 ≤3 people 59.0 50.6 44.8 46.2 44.7
 3–5 people 30.3 34.4 40.0 45.8 46.2
 >5 people 10.7 15.0 15.2 8.1 9.1
BMI at age 25/(kg/m2), (SD) 22.6 (3.2) 22.3 (3.0) 22.0 (2.7) 21.5 (2.5) 21.4 (2.5)
Age at menarche, %
 <15 years old 22.7 19.7 28.9 43.4 58.1
 ≥15 years old 77.3 80.3 71.1 56.6 41.9
Age at menarche/years old, (SD) 16.0 (2.0) 16.3 (2.1) 15.6 (2.0) 14.9 (1.7) 14.3 (1.6)
Oral contraceptive pills use, %
 Never used 94.7 90.3 87.6 90.2 94.6
Age at first birth, %
 ≤21 years old 54.3 45.0 23.9 22.7 24.8
 21–25 years old 30.4 38.4 45.5 59.3 52.8
 ≥25 years old 15.3 16.7 30.6 18.1 22.4
Age at first birth/years old, (SD) 22.0 (3.6) 22.5 (3.4) 24.0 (3.2) 23.5 (2.7) 23.8 (2.9)
Numbers of live births, %
 1 4.4 5.3 36.1 55.9 62.9
 2 8.9 27.8 39.2 32.8 31.3
 >2 86.7 66.9 24.6 11.3 5.8