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Table 2 Unadjusted predictors of term-SGA, preterm-AGA, and preterm-SGA as compared to term-AGA reference

From: Risk factors for small-for-gestational-age and preterm births among 19,269 Tanzanian newborns

Characteristic

Term-AGA

Term-SGA

Preterm-AGA

Preterm-SGA

 

% (n = 13,166)

% (n = 3,051)

Unadjusted RR (95 % CI)

p-value

% (n = 2,989)

Unadjusted RR (95 % CI)

p-value

% (n = 63)

Unadjusted RR (95 % CI)

p-value

Maternal age

          

  < 20 years

12.6

21.1

1.69 (1.54-1.86)

<0.001

16.8

1.37 (1.24–1.52)

<0.001

12.1

2.50 (0.88–7.11)

0.172

 20–25 years

30.1

32.3

1.21 (1.11–1.32)

<0.001

33.9

1.20 (1.01–1.31)

<0.001

43.1

3.73 (1.61–8.61)

0.009

 25–30 years

28.4

24.2

Ref.

 

25.5

Ref.

 

12.1

Ref.

 

 30–35 years

22.0

16.9

0.91 (0.82–1.02)

0.094

17.7

0.91 (0.82–1.01)

0.070

24.2

3.33 (1.35–8.24)

0.007

  ≥ 35 years

6.9

5.6

0.96 (0.82–1.12)

0.582

6.1

0.99 (0.85–1.15)

0.920

8.6

4.55 (1.74–11.94)

0.002

Maternal education

          

 No formal schooling

8.1

6.3

0.78 (0.68–0.90)

<0.001

9.2

1.11 (0.99–1.25)

0.073

9.1

1.22 (0.48–3.09)

0.682

 Some primary

7.1

6.9

0.95 (0.83–1.08)

0.448

8.5

1.17 (1.04–1.32)

0.010

7.3

1.12 (0.40–3.14)

0.828

 Completed primary

73.2

76.6

Ref.

 

72.4

Ref.

 

67.3

Ref.

 

 Secondary plus

11.6

10.2

0.86 (0.77–0.96)

0.009

10.0

0.89 (0.79–1.00)

0.045

16.4

1.52 (0.74–3.15)

0.255

Paternal education

          

 No formal schooling

4.4

3.4

0.78 (0.64–0.94)

0.009

5.8

1.23 (1.06–1.41)

0.005

1.8

0.42 (0.06–3.07)

0.394

 Some primary

4.9

5.1

1.00 (0.86–1.16)

0.986

6.1

1.16 (1.01–1.34)

0.029

5.5

1.13 (0.35–3.64)

0.840

 Completed primary

72.1

74.8

Ref.

 

73.2

Ref.

 

70.9

Ref.

 

 Secondary plus

18.6

16.7

0.89 (0.82–0.98)

0.012

15.0

0.83 (0.75–0.91)

<0.001

21.8

1.19 (0.62–2.28)

0.591

Dar es Salaam wealth quintile

          

 Q1 (Poorest)

15.9

16.3

1.36 (1.08–1.72)

 

15.9

1.35 (1.12–1.64)

 

28.6

3.02 (0.61–14.92)

 

 Q2

20.7

26.2

1.44 (1.16–1.79)

 

20.7

1.21 (1.01–1.45)

 

28.6

2.03 (0.41–10.01)

 

 Q3

14.9

17.2

1.27 (1.01–1.60)

 

14.9

1.16 (0.95–1.40)

 

4.8

0.44 (0.04–4.87)

 

 Q4

25.6

28.8

1.18 (0.95–1.46)

 

25.6

1.10 (0.92–1.31)

 

28.6

1.45 (0.29–7.15)

 

 Q5 (Richest)

11.1

11.5

Ref.

<0.001*

16.8

Ref.

0.001*

9.5

Ref.

0.464*

Morogoro wealth quintile

          

 Q1 (Poorest)

16.4

16.7

0.94 (0.83–1.07)

 

22.2

1.72 (1.49–1.99)

 

14.7

0.95 (0.30–2.99)

 

 Q2

21.3

19.2

0.86 (0.76–0.97)

 

26.7

1.62 (1.41–1.87)

 

17.7

0.88 (0.30–2.62)

 

 Q3

17.2

18.4

0.98 (0.87–1.11)

 

13.8

1.12 (0.95–1.32)

 

11.8

0.73 (0.21–2.48)

 

 Q4

20.1

21.7

0.99 (0.88–1.11)

 

19.2

1.30 (1.12–1.51)

 

35.2

1.86 (0.73–4.72)

 

 Q5 (Richest)

21.9

24.0

Ref.

0.044*

15.3

Ref.

<0.001*

20.6

Ref.

0.544*

Trimester of first ANC visit

          

 1st Trimester

12.9

11.9

0.96 (0.86–1.08)

0.513

11.4

0.90 (0.80–1.01)

0.074

16.0

1.40 (0.65–3.01)

0.393

 2nd Trimester

76.5

76.0

Ref.

 

77.3

Ref.

 

68.0

Ref.

 

 3rd Trimester

10.7

12.2

1.09 (0.98–1.22)

0.125

11.3

1.03 (0.92–1.16)

0.567

16.0

1.68 (0.78–3.61)

0.187

Maternal height

          

  < 150 cm

7.7

12.7

1.90 (1.57–2.31)

 

9.9

1.48 (1.20–1.83)

 

23.3

6.36 (1.65–24.46)

 

 150.0–154.9 cm

33.1

33.5

1.31 (1.11–1.54)

 

36.8

1.33 (1.13–1.55)

 

36.7

2.35 (0.66–8.41)

 

 155.0–159.9 cm

37.9

38.2

1.31 (1.11–1.53)

 

36.5

1.18 (1.01–1.39)

 

30.0

1.69 (0.46–6.21)

 

  ≥ 160.0 cm

21.3

15.6

Ref.

<0.001*

16.8

Ref.

<0.001*

10.0

Ref.

0.011

Parity

          

 First born

26.2

42.5

1.71 (1.59–1.84)

<0.001

31.9

1.25 (1.16–1.34)

<0.001

49.1

2.53 (1.51–4.22)

<0.001

 2nd–4th birth

59.8

49.0

Ref.

 

55.9

Ref.

 

43.4

Ref.

 

 5th or greater

14.0

8.6

0.78 (0.68–0.89)

<0.001

12.2

0.95 (0.85–1.06)

0.386

7.6

0.73 (0.26–2.06)

0.553

Infant sex

          

 Male

51.0

54.0

1.10 (1.03–1.17)

0.004

52.4

1.05 (0.98–1.12)

0.168

50.8

0.99 (0.61–1.62)

0.971

 Female

49.0

46.0

Ref.

 

47.6

Ref.

 

49.2

Ref.

 

Place of birth

          

 Home

8.5

7.4

0.89 (0.79–1.01)

0.06

11.8

1.34 (1.22–1.48)

<0.001

12.7

1.56 (0.75–3.27)

0.236

 Facility

91.5

92.6

Ref.

 

88.2

Ref.

 

87.3

Ref.

 
  1. *p-value for trend
  2. AGA Appropriate for gestational age, ANC Antenatal clinic, CI Confidence interval, SGA Small for gestational age, RR Relative risk