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Table 2 Characteristics of commercially-insured women by preterm birth status, United States, 2011

From: Area-level deprivation and preterm birth: results from a national, commercially-insured population

Characteristic Total N 138,487 Preterm birth N (%) 7870 (5.7) P valuea
Age at delivery (years)    < 0.001
 18–24 16,584 1014 (6.1)  
 25–34 92,117 5001 (5.4)
 35–44 29,786 1855 (6.2)
Census divisionb    < 0.001
 New England 4563 233 (5.1)
 Middle Atlantic 18,565 1000 (5.4)
 East North Central 22,524 1240 (5.5)
 West North Central 10,291 561 (5.5)
 South Atlantic 30,527 1876 (6.1)
 East South Central 7615 473 (6.2)
 West South Central 21,985 1316 (6.0)
 Mountain 11,189 616 (5.5)
 Pacific 11,228 555 (4.9)
Medical factors
 Maternal medical complication
  Hypertension Present 14,511 1500 (10.3) < 0.001
Absent 123,976 6370 (5.1)  
  Gestational diabetes Present 10,639 754 (7.1) < 0.001
Absent 127,848 7116 (5.6)  
  Pre-existing diabetes Present 1753 240 (13.7) < 0.001
Absent 136,734 7630 (5.6)  
  Anaemia Present 3531 230 (6.5) < 0.001
Absent 134,956 7640 (5.7)  
 Infection
  Vaginal, sexually transmitted, and systemic infections Present 38,485 2672 (6.9) < 0.001
Absent 100,002 5198 (5.2)  
 Prior obstetric history
  Incompetent cervix Present 2885 479 (16.6) < 0.001
Absent 135,602 7391 (5.5)  
  Prior preterm birth Present 2674 576 (21.5) < 0.001
Absent 135,813 7294 (5.4)  
  Poor obstetric history Present 5131 513 (10.0) < 0.001
Absent 133,356 7357 (5.5)  
 Obstetric complication
  Premature rupture of membranes Present 1717 178 (10.4) < 0.001
Absent 136,770 7692 (5.6)  
 Fetal complication
  Polyhydramnios Present 3417 279 (8.2) < 0.001
Absent 135,070 7591 (5.6)  
 Mode of delivery    < 0.001
  Cesarean section 49,495 3371 (6.8)  
  Vaginal 88,992 4499 (5.1)  
 Behavioural factors
  Substance use (drug, alcohol, and tobacco use) Present 2153 190 (8.8) < 0.001
Absent 136,334 7680 (5.6)  
 Psychosocial factors
  Mental health condition (depression, anxiety, and other mental disorders) Present 7394 555 (7.5) < 0.001
Absent 131,093 7315 (5.6)  
  1. aP values of bivariate associations between characteristics and preterm birth status obtained from generalized estimating equation models
  2. b The United States census divisions are composed of the following states: New England (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont); Middle Atlantic (New Jersey, New York, Pennsylvania); East North Central (Illinois, Indiana, Michigan, Ohio, Wisconsin); West North Central (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota); South Atlantic (Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia); East South Central (Alabama, Kentucky, Mississippi, Tennessee); West South Central (Arkansas, Louisiana, Oklahoma, Texas); Mountain (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Wyoming, Utah); and Pacific (Alaska, California, Hawaii, Oregon, Washington)