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. Author manuscript; available in PMC: 2017 Sep 1.
Published in final edited form as: Arch Dis Child Fetal Neonatal Ed. 2015 Dec 1;101(5):F433–F438. doi: 10.1136/archdischild-2015-309427

Table 1.

Participant characteristics by birthweight category (N=950*)

Birthweight category (data provided as percentage by category)
<750 g 750–<1000 g 1000–<1250 g 1250–<1500 g
Percentage by birthweight category 14 24 29 32
Variable (% by category, columns add to 100%)
Gender
 Male (50%) 49 56 43 52
 Female (50%) 51 44 57 48
p Value (χ2) 0.02
Gestation
 Extremely preterm (22 to <28 weeks) (33%) 82 58 21   7
 Very preterm (28 to <32 weeks) (50%) 13 36 58 56
 Moderate-to-late preterm (32–<37 weeks) (17%)   5   5 20 31
 Term   0   1   1   6
p Value (χ2) <0.0001
Socio-economic status
 1. High (22%) 24 17 23 24
 2. Medium high (22%) 23 22 22 23
 3. Medium (22%) 21 28 19 20
 4. Medium low (17%) 15 17 19 16
 5. Low (17%) 17 16 17 18
p Value (χ2) 0.6
Parental education
 1. Less than high school (17%) 15 15 15 17
 2. High school (28%) 29 21 27 31
 3. Some college/vocational (28%) 31 36 30 22
 4. College degree (17%) 17 18 15 17
 5. Graduate or doctorate (11%) 8 10 13 12
p Value (χ2) 0.1
Hospital stay
 1–15 days   1   2   4   6
 15–30 days   0   1 14 40
 30–60 days   7 32 49 42
 >60 days 92 65 33 12
<0.0001
Days on ventilator
 0 days 4 10 29 43
 1–15 days 16 34 40 39
 15–30 days 13 23 16   7
 30–60 days 33 22 11   7
 >60 days 34 12   4   4
<0.0001
*

N rounded to the nearest 50 in compliance with National Center for Education Statistics (NCES) guidelines.

NS, not significant (p>0.05).