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Table 3 Register data

From: Assessment of selection bias in a health survey of children and families – the IDEFICS Sweden-study

  

IDEFICS population

Reference population

p-value

n=1 431

n= 1 825

Maternal characteristics

    
 

BMI

23.8 (3.7)

24.0 (3.9)

0.479

n = 1 158

n = 1 305

 

Age (years)

37.8 (4.5)

37.0 (5.2)

<0.001

n = 1 370

n = 1 557

Smoking 3 months before pregnancy

Not smoking

1 071 (86.9%)

1 095 (80.1%)

 
 

1–9 cigarettes/day

73 (5.9%)

133 (9.7%)

 
 

10 or more cigarettes/day

88 (7.1%)

139 (10.2%)

<0.001

Family characteristics

    

Educational level

ISCED (1–2) Low

18 (1.3%)

49 (2.7%)

 
 

ISCED (3–4) Medium

492 (34.4%)

820 (45.0%)

 
 

ISCED (5–6) High

921 (64.4%)

953 (52.3%)

<0.001

Family type

Single parent

112 (7.8%)

269 (14.7%)

 
 

Married or co-habiting

1 319 (92.2%)

1 556 (85.3%)

<0.001

Number of children

One child

168 (11.7%)

287 (15.7%)

 
 

Two or more children

1 263 (88.3%)

1 538 (84.3%)

<0.01

Single or twin birth

Single birth

1 327 (96.9%)

1 510 (97%)

 
 

Twin birth

43 (3.1%)

47 (3.0%)

0.934

Parental origin

Swedish

1 337 (93.4%)

1 599 (87.6%)

 
 

Foreign

94 (6.6%)

226 (12.4%)

<0.001

Family economy

Disposable income/familya

4 943 (2 039)

4 651 (2 527)

<0.001

n = 1 431

n = 1 825

 

Parental personal incomea (one parent)

2 827 (2 445)

2 078 (1 814)

0.004

n = 112

n = 269

 

Social welfare pension/family

26 (1.8%)

85 (4.7%)

<0.001

 

Disability pension/family

45 (3.1%)

103 (5.6%)

<0.001

 

Unemployment compensation/family

141 (9.9%)

243 (13.3%)

0.003

 

Financial study assistance/family

106 (7.4%)

194 (10.6%)

0.002

  1. Maternal characteristics at enrollment in maternity care, and family socioeconomic and sociodemographic characteristics in the IDEFICS and reference populations. Data are presented as the mean with standard deviation (SD) or number and percentage (%).
  2. a The income is in hundred Swedish krona (SEK), e.g. 4 943= SEK 494 300 per year; this sum was equivalent to €53 449 in 2007 (€ 1 = SEK 9.2481).