Skip to main content

Table 1 Characteristics of Age at First Birth, the Ohsaki Cohort, Japan, 1995–2008

From: Age at first birth and long-term mortality for mothers: the Ohsaki cohort study

  Age at first birth (years)
  ≤19 20–24 25–29 ≥30 p-value
No. of subjects 498 13,607 5,625 894  
Age at baseline (%)
 40–49 19.7 18.2 15.4 21.4 <0.01
 50–59 20.5 26.1 24.4 18.9
  ≥ 60 59.8 55.7 60.2 59.7
 Average (SD) 61.3 (11.4) 60.0 (9.9) 60.7 (9.6) 60.3 (10.4) <0.01
Number of births (%)
 1 2.8 3.2 8.1 34.8 <0.01
 2 20.5 33.6 44.2 43.5
 3 28.3 36.5 31.1 15.2
  ≥ 4 48.4 26.8 16.6 6.6
 Average (SD) 3.9 (1.9) 3.1 (1.3) 2.6 (1.1) 2.0 (1.0) <0.01
Use of oral contraceptives (%)
 No 95.0 94.8 96.2 97.0 <0.01
 Yes 5.0 5.2 3.8 3.0
Green vegetables consumption (%)
  ≤ 1–2 times per month 11.1 7.5 7.1 7.0 <0.01
 1–2 times per week 29.2 25.5 25.9 29.1
 3–4 times per week 36.3 36.5 35.8 32.1
 Almost every day 23.5 30.5 31.2 31.8
Carrot or pumpkin consumption (%)
  ≤ 1–2 times per month 17.6 10.6 9.7 10.6 <0.01
 1–2 times per week 32.8 32.0 29.9 33.7
 3–4 times per week 32.6 36.9 38.2 32.5
 Almost every day 17.1 20.4 22.2 23.2
Orange consumption (%)
  ≤ 1–2 times per month 11.6 8.2 8.9 10.8 <0.01
 1–2 times per week 18.5 16.0 16.5 17.7
 3–4 times per week 30.8 30.4 30.0 29.5
 Almost every day 39.1 45.4 44.6 42.1
Green tea consumption (%)
  < 1 cup per day 24.2 22.4 21.7 24.9 0.27
 1–2 cups per day 18.0 20.8 20.6 20.6
 3–4 cups per day 20.1 23.1 23.6 22.6
  ≥ 5 cups per day 37.8 33.6 34.1 32.0
Coffee consumption (%)
  < 1 cup per day 63.9 58.8 60.4 57.0 <0.01
 1–2 cups per day 25.3 31.9 30.5 30.8
 3–4 cups per day 5.1 6.7 6.3 7.8
  ≥ 5 cups per day 5.6 2.6 2.7 4.4
Smoking status (%)
 Current 18.9 7.4 7.0 11.9 <0.01
 Former 2.0 1.9 2.6 4.3
 Never 79.0 90.8 90.4 83.9
Alcohol consumption (%)
 Current 29.3 27.8 22.8 23.7 <0.01
 Former 7.7 4.6 4.1 7.8
 Never 63.1 67.6 73.1 68.5
BMI at baseline in kg/m2 (%)
  < 18.5 3.8 3.2 4.4 4.7 <0.01
 18.5–24 58.1 63.6 65.5 65.2
  ≥ 25.0 38.0 33.2 30.1 30.1
 Average (SD) 24.1 (3.4) 23.9 (3.4) 23.6 (3.4) 23.5 (3.7) <0.01
Increase in body weight since age 20 years (%)
  < 10.0 kg 70.5 76.1 77.8 74.3 <0.01
  ≥ 10.0 kg 29.6 23.9 22.2 25.7
 Average (SD) 4.2 (11.1) 3.5 (9.5) 2.9 (9.6) 3.7 (9.9) <0.01
Walking duration (%)
  < 1 h per day 42.9 46.5 38.3 34.6 <0.01
  ≥ 1 h per day 57.1 53.5 61.7 65.4
Sleeping time (hours per day)
 Average (SD) 7.6 (1.4) 7.5 (1.2) 7.4 (1.2) 7.2 (1.2) <0.01
Defecation frequency (%)
  ≥ 1 time per day 70.7 74.0 73.6 70.3 <0.01
 1 time per 2–3 days 24.4 23.7 24.2 26.0
 1 time per 4–5 days 3.8 2.0 2.0 3.1
  ≤ 1time per 6 days 1.1 0.3 0.3 0.6
Educational level (%)
 Junior high school (<10 years) 83.5 57.5 52.0 42.6 <0.01
 High school (10–12 years) 14.9 36.3 36.2 41.5
 University or higher (≥13 years) 1.6 6.2 11.8 16.0
Ikigai (%)
 Yes 53.5 58.1 57.8 55.8 <0.01
 Uncertain 38.8 37.8 37.7 39.6
 No 7.7 4.1 4.6 4.6  
Perceived mental stress (%)
 High 17.2 17.6 17.6 23.2 <0.01
 Moderate 64.1 66.1 66.3 58.3
 Low 18.8 16.3 16.1 18.5
History of hypertension (%)
 Yes 27.5 27.6 28.3 25.8 0.47
 No 72.5 72.5 71.8 74.2
History of diabetes (%)
 Yes 8.8 5.0 5.3 5.3 <0.01
 No 91.2 95.0 94.7 94.7
  1. Note. BMI body mass index, SD standard deviation
  2. P-value calculated by analysis of variance or χ2 test