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Table 2 Cox Proportional Hazard Ratios (HRs) of Mortality Because of Cardiovascular Disease and Cancer According to 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

 

(n = 498)

(n = 13,607)

(n = 5,625)

(n = 894)

Person-years

5,347

153,247

64,446

9,881

All-cause

 No. of deaths

76

1352

617

120

 Crude HR (95% CI)

1.62 (1.29–2.04)

1.00 (referent)

1.08 (0.99–1.19)

1.38 (1.15–1.67)

  p-value

<0.01

 

0.10

<0.01

 Age at baseline adjusted HR (95% CI)

1.35 (1.07–1.70)

1.00 (referent)

1.05 (0.95–1.15)

1.30 (1.08–1.57)

  p-value

0.01

 

0.34

<0.01

 Multivariate HRa (95% CI)

1.17 (0.92–1.49)

1.00 (referent)

1.09 (0.99–1.20)

1.33 (1.08–1.62)

  p-value

0.21

 

0.09

<0.01

Cancer

 No. of deaths

22

381

178

35

 Crude HR (95% CI)

1.66 (1.08–2.55)

1.00 (referent)

1.11 (0.93–1.33)

1.43 (1.01–2.02)

  p-value

0.02

 

0.25

0.04

 Age at baseline adjusted HR (95% CI)

1.50 (0.98–2.31)

1.00 (referent)

1.08 (0.90–1.29)

1.37 (0.97–1.94)

  p-value

0.06

 

0.42

0.07

 Multivariate HRa (95% CI)

1.31 (0.83–2.06)

1.00 (referent)

1.12 (0.93–1.34)

1.45 (1.00–2.10)

  p-value

0.25

 

0.25

0.051

CVD

 No. of deaths

27

468

195

38

 Crude HR (95% CI)

1.66 (1.13–2.45)

1.00 (referent)

0.99 (0.84–1.17)

1.26 (0.91–1.76)

  p-value

0.01

 

0.90

0.17

 Age at baseline adjusted HR (95% CI)

1.32 (0.89–1.94)

1.00 (referent)

0.96 (0.81–1.14)

1.19 (0.85–1.65)

  p-value

0.17

 

0.64

0.31

 Multivariate HRa (95% CI)

1.11 (0.74–1.67)

1.00 (referent)

0.97 (0.81–1.16)

1.13 (0.77–1.62)

  p-value

0.62

 

0.72

0.51

Other

 No. of deaths

27

503

244

47

 Crude HR (95% CI)

1.55 (1.05–2.28)

1.00 (referent)

1.15 (0.99–1.34)

1.46 (1.08–1.97)

  p-value

0.03

 

0.07

0.01

 Age at baseline adjusted HR (95% CI)

1.25 (0.85–1.83)

1.00 (referent)

1.11 (0.96–1.30)

1.37 (1.01–1.84)

  p-value

0.26

 

0.16

0.04

 Multivariate HRa (95% CI)

1.11 (0.74–1.65)

1.00 (referent)

1.20 (1.02–1.41)

1.43 (1.03–1.99)

  p-value

0.61

 

0.03

0.03

  1. Note. CI confidence interval, CVD cardiovascular disease, HR hazard ratio
  2. a The multivariate HR has been adjusted for age at baseline (continuous variable), number of births (1, 2, 3, or ≥4), use of oral contraceptives (yes or no), consumption of green vegetables, carrot or pumpkin, orange (for each food, ≤1–2 times per month, 1–2 times per week, 3–4 times per week, or almost every day), consumption of coffee (<1, 1–2, 3–4, or ≥5 cups per day), smoking status (never, former, or currently smoking), alcohol drinking (never, former, or currently drinking), body mass index at baseline in kg/m2 (<18.5, 18.5–24.9, or ≥25.0), increase in body weight since age 20 years (<10.0 or ≥10.0 kg), walking duration (<1 or ≥1 h per day), sleeping time in hours per day (continuous variable), defecation frequency (≥1 time per day, 1 time per 2–3 days, 1 time per 4–5 days or ≤1 time per 6 days), years of education (<10, 10–12, or ≥13 years), ikigai (yes, uncertain, or no), perceived mental stress (high, moderate, or low), and history of diabetes (yes or no)
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Environmental Health and Preventive Medicine

ISSN: 1347-4715

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