Table 2 Results of the univariate analyses on HDP for the covariates (total n = 44,747)

From: Secondhand smoke exposure is associated with the risk of hypertensive disorders of pregnancy: the Japan Environment and Children’s Study

  

RR

95% CI

Frequency of SHS exposure

rarely

Reference

 
 

1–3 days/week

1.148

1.007–1.309

 

4–7 days/week

1.346

1.167–1.554

Duration of SHS exposure

<1 h

Reference

 
 

1–2 h

1.489

1.213–1.826

 

≥2 h

1.481

1.125–1.950

Age (years)

<20

Reference

 
 

20–24

0.975

0.397–2.395

 

25–29

0.976

0.407–2.338

 

30–34

1.054

0.441–2.520

 

35–39

1.597

0.668–3.820

 

≥40

2.345

0.969–5.678

Parity

primipara

1.953

1.746–2.184

 

multipara

Reference

 

BMI (kg/m2)

<18.5

0.636

0.524–0.771

 

18.5–24.9

Reference

 
 

≥25.0

3.000

2.642–3.407

Alcohol consumption

no drinking

Reference

 
 

quit before or during pregnancy

0.912

0.813–1.023

 

continued drinking

0.882

0.726–1.073

K6 score

<13

Reference

 
 

≥13

1.080

0.779–1.497

Maternal educational level

junior high school

1.053

0.656–1.690

 

high school

1.135

1.002–1.286

 

college

Reference

 

Family income (×104 JPY)

<200

Reference

 
 

200–399

0.949

0.776–1.160

 

400–599

0.855

0.699–1.045

 

600–799

0.995

0.803–1.233

 

≥800

0.873

0.670–1.138

Sodium intake

Q1

Reference

 
 

Q2

0.865

0.729–1.027

 

Q3

0.850

0.716–1.011

 

Q4

0.898

0.758–1.064

 

Q5

0.990

0.839–1.168

Pottasium intake (mg/day)

Q1

Reference

 
 

Q2

0.941

0.791–1.119

 

Q3

1.030

0.869–1.220

 

Q4

0.972

0.818–1.154

 

Q5

0.984

0.829–1.168

Calcium intake (mg/day)

Q1

Reference

 
 

Q2

1.180

0.999–1.394

 

Q3

1.014

0.853–1.206

 

Q4

0.945

0.793–1.127

 

Q5

0.924

0.774–1.103

Magnesium intake (mg/day)

Q1

Reference

 
 

Q2

0.999

0.840–1.061

 

Q3

0.989

0.831–1.118

 

Q4

1.067

0.900–1.037

 

Q5

0.997

0.000–1.087

Salt intake (g/day)

Q1

Reference

 
 

Q2

0.845

0.710–1.006

 

Q3

0.872

0.735–1.034

 

Q4

0.891

0.753–1.054

 

Q5

0.991

0.840–1.169

Total Energy intake (kJ/day)

Q1

Reference

 
 

Q2

0.912

0.764–1.088

 

Q3

1.019

0.858–1.211

 

Q4

0.968

0.813–1.152

 

Q5

1.124

0.950–1.329

History of gestational diabetes

 

1.657

0.951–2.170

History of HDP

 

6.762

5.571–8.207

Partner smoking status

no smoking

Reference

 
 

quit before pregnancy

0.962

0.835–1.109

 

quit during pregnancy

0.906

0.582–1.410

 

continued smoking

1.048

0.923–1.191

Partner’s educational level

junior high school

1.210

0.916–1.600

 

high school

1.171

1.043–1.315

 

college

Reference

 
  1. RR relative risk, CI confidence interval, HDP hypertensive disorders of pregnancy, JPY Japanese yen, K6 Kessler psychological distress scale, SHS secondhand smoke, BMI body mass index
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