Table 3 Association between the frequency and duration of secondhand smoke exposure and HDP among nonsmokers

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

  

Relative Risk

95% CI

 

Frequency of maternal SHS exposure before pregnancy

  

Crude

rarely

Reference

 

1–3 days/week

1.148

1.007–1.309

4–7 days/week

1.346

1.167–1.554

Model 1

rarely

Reference

 

1–3 days/week

1.076

0.943–1.228

4–7 days/week

1.197

1.032–1.387

Model 2

rarely

Reference

 

1–3 days/week

1.052

0.921–1.200

4–7 days/week

1.189

1.027–1.376

Model 3

rarely

Reference

 

1–3 days/week

1.046

0.917–1.195

4–7 days/week

1.177

1.017–1.363

 

Duration of maternal SHS exposure before pregnancy

  

Crude

<1 h

Reference

 

1–2 h

1.489

1.213–1.826

≥2 h

1.481

1.125–1.950

Model 1

<1 h

Reference

 

1–2 h

1.315

1.073–1.613

≥2 h

1.304

0.992–1.714

Model 2

<1 h

Reference

 

1–2 h

1.282

1.049–1.566

≥3 h

1.276

0.968–1.681

Model 3

<1 h

Reference

 

1–2 h

1.270

1.039–1.551

≥2 h

1.266

0.960–1.670

  1. Model 1: Adjusted for age, parity, body mass index before pregnancy, family income, maternal educational level, drinking status, Na, K, Ca, Mg, and total energy intake, and K6 score
  2. Model 2: Adjusted for a history of GDM and HDP in addition to the factors in Model 1
  3. Model 3: Adjusted for partner’s educational level in addition to the factors in Model 2
  4. SHS secondhand smoke, HDP hypertensive disorders of pregnancy, GDM gestational diabetes mellitus, K6 Kessler psychological distress scale, CI confidence interval
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