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Table 3 Trends of birth weight categories, singletons and multiples live births in Chile 1991-2008

From: Trends in gestational age and birth weight in Chile, 1991–2008. A descriptive epidemiological study

Period

1991-1995

1996-2000

2001-2008

P1a

P2

P3

P1P2

P2P3

P1P3

Overall Trend

Total population

1 344 067

1 253 164

1 870 502

          

N = 4 467 733

 

Birth weighte

Rate %

 

95% CIb

 

% change

P c

% change

P

% change

P

P d

<1500

0.61

0.72

0.88

[0.60-0.62]

[0.70-0.73]

[0.87-0.90]

18

< 0.000

22.2

< 0.000

44.3

< 0.000

< 0.000

1500-2499

4.02

3.99

4.39

[4.00-4.05]

[3.95-4.02]

[4.36-4.41]

−0.7

< 0.000

10.0

< 0.000

9.2

< 0.000

0.126

2500-3999

87.27

86.43

86.01

[87.22-87.33]

[86.37-86.49]

[85.96-86.06]

−1.0

< 0.000

−0.5

< 0.000

−1.4

< 0.000

< 0.000

4000-max

8.10

8.86

8.72

[8.05-8.15]

[8.80-8.90]

[8.68-8.77]

9.4

< 0.000

−1.6

< 0.000

7.7

0.00

0.190

Singletons

(1 323 021)

(1 232 824)

(1 836 582)

          

(4 392427)

 

<1500

0.53

0.62

0.75

[0.52-0.54]

[0.60-0.63]

[0.74-0.76]

17.0

< 0.000

21.0

< 0.000

41.5

< 0.000

< 0.000

1500-2499

3.44

3.38

3.65

[3.42-3.48]

[3.35-3.41]

[3.60-3.70]

−1.7

< 0.000

8.0

< 0.000

6.1

< 0.000

0.274

2500-3999

87.80

87.00

86.70

[87.74-87.85]

[86.94-87.06]

[86.64-86.77]

−0.9

0.000

−0.3

< 0.000

−1.3

< 0.000

0.003

4000-max

8.23

9.00

8.90

[8.17-8.27]

[8.95-9.05]

[8.83-8.92]

9.4

< 0.000

−1.1

< 0.000

8.1

0.000

0.176

Multiples (75 306)

(21 046)

(20 340)

(33 920)

          

<1500

5.53

6.70

7.89

[5.20-5.80]

[6.40-6.90]

[7.60-8.20]

21.2

< 0.000

17.8

< 0.000

42.7

< 0.000

< 0.000

1500-2499

39.87

40.77

44.43

[39.20-40.53]

[40.09-41.44]

[43.90-45.02]

2.3

0.01

9.0

< 0.000

11.4

< 0.000

0.006

2500-3999

54.38

52.37

47.52

[53.71-55.06]

[51.69-53.06]

[47.00-48.05]

−3.7

< 0.000

−9.3

< 0.000

−12.6

< 0.000

< 0.001

4000-max

0.22

0.16

0.15

[0.16-0.28]

[0.10-0.21]

[0.11-0.19]

−27.3

< 0.000

−6.3

< 0.000

−31.8

<0.000

0.560

  1. aPeriods: P1: 1991–1995, P2: 1996–2000, P3:2001–2008.
  2. b95% confidence interval.
  3. cPearson’s chi-square test with significance level for p < 0.05.
  4. dPrais-Winsten Regression analysis for trend with significance level for p < 0.05.
  5. eBirth weight in grams.