Table 1 Sample characteristics, live births, Tarrant County, 2006–2010 (n = 145,054)

Maternal Race/Ethnicity

<0.001

 Caucasian, non-Hispanic

60,156 (41.5)

708 (1.2)

59,442 (98.8)

 African American, non-Hispanic

22,306 (15.4)

689 (3.1)

21,615 (96.9)

 Hispanic

54,553 (37.6)

659 (1.2)

53,892 (98.8)

 Other, non-Hispanic

8,039 (5.5)

98 (1.2)

7,937 (98.8)

Maternal Age

<0.001

 < 20 years

17,117 (11.8)

290 (1.7)

16,827 (98.3)

 20-39 years

124,865 (86.1)

1,792 (1.4)

123,061 (98.6)

   40 years

3,069 (2.1)

72 (2.3)

2,996 (97.7)

Maternal Education

0.008

 < High school

37,899 (26.1)

526 (1.4)

37,370 (98.6)

 High school

38,259 (26.4)

628 (1.6)

37,627 (98.4)

 > High school

68,839 (47.5)

996 (1.4)

67,838 (98.6)

Kotelchuck Index

<0.001

 Adequate Plus

32,235 (22.2)

915 (2.8)

31,318 (97.2)

 Adequate

53,286 (36.7)

229 (0.4)

53,056 (99.6)

 Intermediate

12,300 (8.5)

212 (1.7)

12,088 (98.3)

 Inadequate

44,841 (30.9)

695 (1.6)

44,142 (98.4)

Plurality

<0.001

 Single

140,408 (96.8)

1,623 (1.2)

138,772 (98.8)

 Multiple

4,643 (3.2)

531 (11.4)

4,112 (88.6)

Previous Preterm Birth

<0.001

 No

143,220 (98.7)

2,073 (1.4)

141,134 (98.6)

 Yes

1,834 (1.3)

81 (4.4)

1,752 (95.6)

STD During Pregnancy

0.462

 No

140,406 (96.8)

2,079 (1.5)

138,313 (98.5)

 Yes

4,648 (3.2)

75 (1.6)

4,573 (98.4)

Smoking

0.002

 No

137,652 (94.9)

2,012 (1.5)

135,627 (98.5)

 Yes

7,402 (5.1)

142 (1.9)

7,259 (98.1)

Paternal Race/Ethnicity

<0.001

 Caucasian, non-Hispanic

52,356 (36.1)

590 (1.1)

51,763 (98.9)

 African American, non-Hispanic

17,821 (12.3)

487 (2.7)

17,333 (97.3)

 Hispanic

46,894 (32.3)

531 (1.1)

46,362 (98.9)

 Other, non-Hispanic

6,612 (4.6)

79 (1.2)

6,533 (98.8)

 Missing

21,371 (14.7)

467 (2.2)

20,895 (97.8)

Mother Marital Status

<0.001

 Married

87,078 (60.0)

1,131 (1.3)

85,940 (98.7)

 Not married

57,970 (40.0)

1,023 (1.5)

56,942 (98.2)