Table 2 Decomposition of concentration index for congenital heart disease in Iran

Socio-economic status

Poorest

0.59

0.20

−0.57

− 0.27

41.39

Poorer

0.55

0.20

−0.28

− 0.12

18.95

Middle

0.27

0.23

0.05

0.01

−1.91

Richer

0.24

0.18

0.33

0.06

−8.77

Richest

Ref

–

–

–

–

Sum

49.66

Mother’s education

Illiterate

0.14

0.14

−0.25

−0.02

3.02

Primary school

0.08

0.19

−0.21

− 0.01

1.96

Middle school

0.01

0.24

−0.06

0.00

0.09

High school

0.07

0.24

0.14

0.01

−1.45

University

Ref

–

–

–

–

Sum

3.62

Father’s education

Illiterate

−0.19

0.06

0.04

0.00

0.28

Primary school

−0.21

0.09

−0.19

0.01

−2.21

Middle school

−0.25

0.17

−0.28

0.05

−7.32

High school

−0.10

0.29

−0.08

0.01

−1.43

University

Ref

–

–

–

–

Sum

−10.68

Mother’s occupation

Housewife

0.11

0.61

−0.40

− 0.11

16.52

Clerical jobs

−0.08

0.23

0.40

−0.03

4.53

Non-clerical jobs

Ref

–

–

–

–

Sum

21.05

Father’s occupation

Clerical jobs

0.20

0.38

0.63

0.19

−29.46

Non-clerical jobs

0.19

0.56

−0.38

− 0.16

24.88

Unemployed

Ref

–

–

–

–

Sum

−4.58

Nationality

Iranian

0.13

0.96

0.05

0.02

−3.84

Non-Iranian

Ref

–

–

–

–

Place of residence

Urban

0.00

0.82

0.29

0.00

0.00

Rural

Ref

–

–

–

–

Number of children

One child

−0.16

0.34

− 0.05

0.01

−1.67

Two children

−0.09

0.44

0.06

−0.01

1.46

> = 3 children

Ref

–

–

–

–

−0.21

History of family marriage

Yes

−0.10

0.24

−0.24

0.02

−3.54

No

Ref

–

–

–

–

Total social variables

51.47

Mother’s age at delivery time

≤17 (yr)

−0.01

0.02

−0.05

0.00

−0.01

18–28 (yr)

0.04

0.34

−0.09

0.00

0.75

29–39 (yr)

0.10

0.52

0.13

0.03

−4.16

> = 40 (yr)

–

–

–

–

–

Sum

−3.41

Father’s age

17–25 (yr)

0.17

0.08

−0.12

−0.01

1.00

26–30 (yr)

0.15

0.18

0.07

0.01

−1.16

31–35 (yr)

0.13

0.23

−0.09

− 0.01

1.66

36–40 (yr)

−0.02

0.29

0.09

0.00

0.32

> 41 (yr)

Ref

–

–

–

–

Sum

1.82

Pregnancy care

Have

−0.16

0.80

0.28

−0.14

22.06

Not have

Ref

–

–

–

–

History of abortion

Yes

0.10

0.23

−0.38

− 0.03

5.38

No

Ref

–

–

–

–

Chronic disease

Have

0.03

0.33

−0.28

− 0.01

1.71

Not have

Ref

–

–

–

–

Using folic acid

Yes

−0.11

0.80

0.29

−0.10

15.70

No

Ref

–

–

–

–

Total Medical/biological variable

43.25

Physical activity

Enough

0.01

0.67

0.15

0.00

−0.62

Not enough

Ref

–

–

–

–

Using alcohol

Yes

0.07

0.20

−0.31

− 0.02

2.67

No

Ref

–

–

–

–

Smoking

Yes

0.05

0.19

- 0.32

−0.01

1.87

No

Ref

–

–

–

–

Total life style

3.92

Total observed

−0.64

98.64

Residual

−0.01

1.36

Total

−0.65

100.00