Skip to main content

Table 2 Univariate difference between training sample and validation sample

From: Subgroup identification of early preterm birth (ePTB): informing a future prospective enrichment clinical trial design

Variables

Cohort

Training

Validation

N = 2796411

N = 1198461

Mothers’ Age (%)

  ≤ 24 Years

794486 (28.41)

341018 (28.45)

 25-29 Years

803113 (28.72)

344361 (28.73)

 30-34 Years

758087 (27.11)

325266 (27.14)

  ≥ 35 Years

440725 (15.76)

187816 (15.67)

Mothers’ Nativity (%)

 Born in U.S.

2172903 (77.70)

931206 (77.70)

 Born Outside U.S. /Unknown/Not Stated

623508 (22.30)

267255 (22.30)

Mothers’ Race (%)

 White

2119115 (75.78)

907536 (75.73)

 Black

447972 (16.02)

192503 (16.06)

 American Indian/Alaskan Native/Asian or Pacific Islander

229324 (8.20)

98422 (8.21)

Mothers’ Hispanic Origin (%)

 Non-Hispanic/Hispanic Origin Not Stated

2151766 (76.95)

921667 (76.90)

 Hispanic

644645 (23.05)

276794 (23.10)

Marital Status (%)

 Married

1672583 (59.81)

716631 (59.80)

 Unmarried

1123828 (40.19)

481830 (40.20)

Mothers’ Education (%)

  ≤ High School or GED/Unknown

1102757 (39.43)

472551 (39.43)

 Associate/Some College Credit

786618 (28.13)

336873 (28.11)

  ≥ Bachelor's

806822 (28.85)

346400 (28.90)

 Missing

100214 (3.58)

42637 (3.56)

Pre-pregnancy Smoking Status (%)

 Nonsmoker

2357285 (84.30)

1009935 (84.27)

 Smoker/Unknown/Not Stated

338912 (12.12)

145889 (12.17)

 Missing

100214 (3.58)

42637 (3.56)

Pre-pregnancy BMI (%)

 Under Weight-Normal ≤ 24.9

1288811 (46.09)

552926 (46.14)

 Overweight 25.0-29.9

664673 (23.77)

283995 (23.70)

 Obesity ≥ 30.0/Unknown/Not Stated

742713 (26.56)

318903 (26.61)

 Missing

100214 (3.58)

42637 (3.56)

Pre-pregnancy Diabetes Status (%)

 No/Unknown/Not Stated

2675048 (95.66)

1146820 (95.69)

 Yes

21149 (0.76)

9004 (0.75)

 Missing

100214 (3.58)

42637 (3.56)

Pre-pregnancy Hypertension Status (%)

 No/Unknown/Not Stated

2653410 (94.89)

1137811 (94.94)

 Yes

42787 (1.53)

18013 (1.50)

 Missing

100214 (3.58)

42637 (3.56)

Previous Preterm Birth Status (%)

 No/Unknown/Not Stated

2621496 (93.75)

1123851 (93.77)

 Yes

74701 (2.67)

31973 (2.67)

Missing

100214 (3.58)

42637 (3.56)

Infertility Treatment Usage Status (%)

 No/Unknown/Not Stated

2654757 (94.93)

1137952 (94.95)

 Yes

41440 (1.48)

17872 (1.49)

 Missing

100214 (3.58)

42637 (3.56)

Fertility Enhancing Drug Usage Status (%)

 No/Not Applicable/Unknown/Not Stated

2676910 (95.73)

1147528 (95.75)

 Yes

19287 (0.69)

8296 (0.69)

 Missing

100214 (3.58)

42637 (3.56)

Delivery Payment Source (%)

 Medicaid

1164617 (41.65)

499282 (41.66)

 Private Insurance

1276362 (45.64)

547205 (45.66)

 Self-pay/Other/Unknown

255218 (9.13)

109337 (9.12)

 Missing

100214 (3.58)

42637 (3.56)

Newborn Gestational Age (%)

  < 34 weeks: ePTB

93751 (3.35)

40258 (3.36)

  ≥ 34 weeks

2702660 (96.65)

1158203 (96.64)