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Table 3 Characteristics of the participants stratified according to duration of breastfeeding

From: Duration of breastfeeding, age at introduction of complementary foods and allergy-related diseases: a prospective cohort study

 

Duration of any breastfeeding (N = 6796)

≥ 6 months (n = 5695)

<  6 months (n = 1101)

Characteristics

na

 

na

 

Maternal age at birth, years, mean (SD)

5670

30.2 (4.4) range: 16.8–44.5

1095

28.7 (5.1) range: 17.0–44.2

Maternal education, n (%)

2625

 

392

 

<  12 years (less than high school)

 

116 (4.4)

 

62 (15.8)

12–16 years (up to 4 years university)

 

1298 (49.5)

 

237 (60.5)

>  16 years (more than 4 years university)

 

1211 (46.1)

 

93 (23.7)

Mean incomeb, NOK, mean (SD)

5465

255,414 (29175)

1053

250,191 (30405)

Family history of allergyc, n (%)

5675

4200 (74.0)

1092

784 (71.8)

Older sibling, n (%)

3943

2245 (56.9)

731

401 (54.9)

Maternal smoking, n (%)

    

During pregnancy

2020

92 (4.6)

316

55 (17.4)

During child’s first 2 years

5638

887 (15.7)

1078

391 (36.3)

Paternal smoking, n (%)

5397

1072 (19.9)

994

330 (33.2)

Child exposed to smoke during first 2 yearsd, n (%)

5675

1462 (25.8)

1095

502 (45.8)

Petse, n (%)

5695

1143 (20.1)

1101

264 (24.0)

Birthweight, gram, mean (SD)

5625

3608 (552) range: 640–5560

1072

3463 (705) range: 585–5960

Birthweight < 2500 g, n (%)

5625

156 (2.8)

1072

88 (8.2)

Sex, male, n (%)

5693

2798 (49.2)

1101

581 (52.8)

Lower respiratory tract infection within first yearf, n (%)

3217

333 (10.4)

606

78 (12.9)

Antibiotic treatment within first year, n (%)

3746

756 (20.2)

695

163 (23.5)

Introduced to formula < 6 months of age, n (%)

5625

966 (17.2)

1093

972 (88.9)g

Start of day-care < 12 months of age, n (%)

5051

394 (7.8)

930

65 (7.0)

  1. a:The numbers vary because of missing data
  2. b: Yearly income in Norwegian krone based on postcode (range: 174967 to 319,333 for both groups)
  3. c: Mother, father or common child with parental reported asthma, ARC or eczema
  4. d: Parental or indoor smoking; e: Reported cat, dog or other furry pets
  5. f: Pneumonia or bronchitis
  6. g: questionnaire data indicates children started with formula after 6 months of age despite having been weaned before 6 months