TABLE 7.

Multivariable Analysis of Variables Associated With Low MDI

Variables	<55	55–69
Total sample (n = 921)
Gestational age 23–24 wk	1.9 (0.97, 3.6)	1.0 (0.5, 1.9)
Gestational age 25–26 wk	1.2 (0.7, 2.1)	0.8 (0.5, 1.3)
Single mother	1.3 (0.7, 2.2)	1.2 (0.7, 2.1)
BMI >30	1.9 (1.1, 3.1)a	1.3 (0.9, 2.3)
Vaginal/cervical infection	1.2 (0.6, 2.2)	1.4 (0.8, 2.6)
Cesarean delivery	0.8 (0.5, 1.2)	0.8 (0.5, 1.4)
BWZ < –2	2.2 (1.5, 7.5)a	1.9 (0.7, 4.8)
Male	2.5 (1.6, 4.1)a	2.0 (1.3, 3.2)a
Nonwhite race	2.3 (1.4, 3.8)a	2.1 (1.3, 3.5)a
Mother's education <12 y	2.8 (1.6, 4.9)a	0.9 (0.5, 1.8)
Mother's education >16 y	0.8 (0.4, 1.5)	0.7 (0.4, 1.2)
Total histology/BSID sample (n = 857)
Gestational age 23–24 wk	1.9 (0.9, 3.9)	1.1 (0.6, 2.1)
Gestational age 25–26 wk	1.1 (0.6, 2.0)	0.8 (0.4, 1.3)
Single mother	1.2 (0.7, 2.2)	1.2 (0.7, 2.0)
BMI >30	2.0 (1.1, 3.5)a	1.2 (0.7, 2.1)
Vaginal/cervical infection	1.2 (0.6, 2.4)	1.4 (0.7, 2.7)
Cesarean delivery	0.9 (0.5, 1.5)	0.9 (0.5, 1.5)
BWZ < –2	2.8 (1.1, 6.9)a	1.9 (0.7, 5.0)
Male	2.7 (1.6, 4.5)a	2.1 (1.3, 3.4)a
Thrombosis fetal vessels	3.1 (1.2, 7.7)a	0.6 (0.1, 2.5)
Increased syncytial knots	1.4 (0.8, 2.5)	1.5 (0.9, 2.5)
Nonwhite race	2.2 (1.3, 3.8)a	2.2 (1.3, 3.7)a
Mother's education <12 y	3.4 (1.9, 6.2)a	1.1 (0.6, 2.2)
Mother's education >16 y	0.7 (0.4, 1.4)	0.7 (0.4, 1.3)

Risk ratios and 95% CIs. The referent group is infants with MDI ≥70. BWZ, birthweight z score.

^ap < .05.