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Table 2 Relative risks (RRs) with 95% confidence intervals (95% CIs) of adequate maternal periconceptional folic acid supplement use (before and during pregnancy) by paternal characteristics, in 683,785 births, Norway, 1999–2010

From: Paternal characteristics associated with maternal periconceptional use of folic acid supplementation

 

Folic acid supplementation use

Unadjusted

Adjusted for paternal factors a b

Further adjusted for maternal factors a c

Characteristics

Yes

No

RR*

95% CI

RR*

95% CI

RR*

95% CI

Paternal age (years)

 < 20

86

4315

0.11

0.09–0.13

0.10

0.08–0.13

0.35

0.28–0.43

 20–24

3325

45,123

0.37

0.36–0.39

0.37

0.36–0.38

0.68

0.66–0.71

 25–29

22,886

139,785

0.76

0.75–0.78

0.77

0.76–0.79

0.94

0.93–0.96

 30–34

43,348

192,053

1.00

Reference

1.00

Reference

1.00

Reference

 35–39

28,488

123,052

1.02

1.01–1.03

0.97

0.96–0.99

0.90

0.89–0.91

 40+

12,733

68,591

0.85

0.83–0.87

0.80

0.78–0.81

0.72

0.71–0.74

Paternal education

 Compulsory (1–10 years)

11,694

119,259

0.40

0.39–0.40

0.52

0.51–0.53

0.69

0.68–0.71

 Intermediate (11–13 years)

45,411

256,973

0.67

0.66–0.67

0.75

0.74–0.76

0.87

0.85–0.88

 Tertiary (14–20 years)

51,894

177,924

1.00

Reference

1.00

Reference

1.00

Reference

 Missing data

1867

18,763

      

Paternal occupational class d

 I Higher professionals

19,957

66,678

1.05

1.04–1.07

1.05

1.03–1.06

  

 II Lower professionals

33,366

119,415

1.00

Reference

1.00

Reference

  

 IIIa Higher routine

12,292

65,248

0.73

0.71–0.74

0.89

0.88–0.91

  

 IIIb Lower routine

5352

34,718

0.61

0.59–0.63

0.85

0.83–0.87

  

 IV Other self-employed workers

60

298

0.77

0.61–0.97

0.83

0.65–1.05

  

 V Technicians

836

4714

0.69

0.65–0.74

0.89

0.84–0.95

  

 VI Skilled

15,174

93,581

0.64

0.63–0.65

0.84

0.83–0.86

  

 VII Semiskilled and unskilled

11,643

99,941

0.48

0.47–0.49

0.75

0.73–0.76

  

 VIIb Agricultural

908

6755

0.54

0.51–0.58

0.73

0.69–0.78

  

 Unclassified

7575

45,249

0.66

0.64–0.67

0.96

0.94–0.99

  

 Missing data

3703

36,322

      

Paternal country of origin e

 Norway

99,339

475,263

1.00

Reference

1.00

Reference

1.00

Reference

 High income countries

6535

26,952

1.13

1.10–1.16

1.06

1.04–1.09

1.06

1.03–1.08

 Low-middle-income countries

4975

70,522

0.38

0.37–0.39

0.35

0.34–0.36

0.58

0.56–0.60

 Missing data

17

182

      
  1. aAll RRs for adequate folic acid supplementation adjusted for year of childbirth (continuous)
  2. bRRs by paternal age, no other adjustment for paternal factors; RRs by paternal education adjusted for paternal age (< 20, 20–24, 25–29, 30–34, 35–39, 40+), paternal country of origin (Norway, high-income countries, low/middle-income countries); RRs by paternal occupation adjusted for paternal age, fathers country of origin, fathers education (compulsory, intermediate, tertiary); and RR by paternal origin of country, no other adjustment for paternal factors
  3. cRRs by paternal age, further adjusted for maternal age (< 20, 20–24, 25–29, 30–34, 35–39, 40+); RRs by paternal education, further adjusted for maternal education (compulsory, intermediate, tertiary); RRs by paternal occupation, no further adjustment for maternal factors; RRs by paternal country of origin adjusted for maternal country of origin (Norway, High-income countries, Low/middle-income countries)
  4. dCategorized according to the class scheme of Erikson, Goldthorpe and Portocarero (EGP) [33]
  5. eCategorized according to the classification by World Health Organization, Health statistics and information systems, Estimates for 2000–2012 [34]
  6. *p-value for difference between categories of paternal characteristics was < 0.001 using likelihood ratio test
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BMC Pregnancy and Childbirth

ISSN: 1471-2393

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