Table 1 Demographic data for the preterm and matched term infants.

From: Premature birth carries a higher risk of nephrotic syndrome: a cohort study

 

Preterm (n = 78,651)

Term (n = 786,510)

p value

Male, n (%)

44,960 (57.2)

449,600 (57.2)

1.000

Birth year, n (%)

1.000a

 2004

14,232 (18.1)

142,320 (18.1)

 

 2005

13,066 (16.6)

130,660 (16.6)

 

 2006

12,805 (16.3)

128,050 (16.3)

 

 2007

12,896 (16.4)

128,960 (16.4)

 

 2008

13,195 (16.8)

131,950 (16.8)

 

 2009

12,457 (15.8)

124,570 (15.8)

 

Gestational age groups, n (%)

 ≤ 28 wks

2158 (2.7)

0 (0.0)

 

 29–31 wks

3804 (4.8)

0 (0.0)

 

 32–36 wks

72,689 (92.4)

0 (0.0)

 

 ≥ 37 wks

0 (0.0)

786,510 (100.0)

 

SGA, n (%)

5202 (6.6)

76,769 (9.8)

 < 0.001***

Urbanization level, n (%)

 < 0.001***b

 1 or 2 (lowest)

7374 (9.4)

63,834 (8.1)

 

 3 or 4

13,574 (17.3)

130,050 (16.5)

 

 5

18,705 (23.8)

182,671 (23.2)

 

 6

23,305 (29.6)

241,865 (30.8)

 

 7

15,693 (20.0)

168,090 (21.4)

 

Family income, quartile, n (%)

 < 0.001***c

 Dependent or first

22,698 (28.9)

185,418 (23.6)

 

 Second

20,127 (25.6)

202,274 (25.7)

 

 Third

18,422 (23.4)

198,856 (25.3)

 

 Fourth

17,404 (22.1)

199,962 (25.4)

 

Maternal age, year, mean (SD)

29.8 (5.2)

29.4 (4.8)

 < 0.001***

Paternal age, year, mean (SD)

33.0 (5.7)

32.6 (5.3)

 < 0.001***

Maternal complication, n (%)

 

 RA

139 (0.2)

994 (0.1)

 < 0.001***

 SLE

427 (0.5)

1852 (0.2)

 < 0.001***

 DM

1819 (2.3)

7246 (0.9)

 < 0.001***

 GDM

8855 (11.3)

81,927 (10.4)

 < 0.001***

 Chronic HTN

2600 (3.3)

6134 (0.8)

 < 0.001***

 PIH

5266 (6.7)

14,631 (1.9)

 < 0.001***

 Asthma

401 (0.5)

2635 (0.3)

 < 0.001***

  1. The family income was assessed at birth and was classified into four quartiles based on each birth year. PIH was defined as hypertension that complicated pregnancy after 20 weeks of gestation.
  2. DM diabetes mellitus, GDM gestational diabetes mellitus, HTN hypertension, PIH pregnancy-induced hypertension, RA rheumatoid arthritis, SGA small for gestational age, SLE systemic lupus erythematosus.
  3. aThe p value implied the differences of the birth year distributions between preterm and term infants.
  4. bThe p value implied the differences of urbanization distributions between preterm and term infants.
  5. cThe p value implied the differences of family income distributions between preterm and term infants.
  6. ***p < 0.001.
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