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Table 1 Characteristics of the study population by maternal age groups (N = 8509)

From: Birth outcomes across the spectrum of maternal age: dissecting aging effect versus confounding by social and medical determinants

Maternal Characteristics < 20 years 20–29 years 30–39 years 40+ years Total P-valuea
N % N % N % N % N %
Total 907 100 4305 100 2960 100 337 100 8509 100
Sociodemographic
Race/ethnicity < 0.001
  Blackb 488 53.8 2073 48.2 1613 54.5 219 65.0 4393 51.6  
  Non-Black 419 46.2 2232 51.8 1347 45.5 118 35.0 4116 48.4  
Parity < 0.001
  Nulliparous 760 83.8 2103 48.9 751 25.4 49 14.5 3663 43.0  
  Multiparous 147 16.2 2202 51.1 2209 74.6 288 85.5 4846 57.0  
Education (n = 8349) < 0.001
   < College 813 91.3 2733 64.9 1658 56.9 219 66.0 5423 65.0  
   ≥ College 77 8.7 1479 35.1 1257 43.1 113 34.0 2926 35.0  
Marital Status (n = 8340) < 0.001
  Not married 842 94.8 2984 70.8 1473 50.7 170 51.5 5469 65.6  
  Married 46 5.2 1232 29.2 1433 49.3 160 48.5 2871 34.4  
Public assistancec (n = 8378) 0.580
  No 157 17.5 813 19.2 572 19.6 63 18.9 1605 19.2  
  Yes 738 82.5 3423 80.8 2341 80.4 271 81.1 6773 80.8  
Yearly Income in US$ (n = 7616) < 0.001
   ≥ $30,000 18 2.3 470 12.1 547 20.7 59 19.2 1094 14.4  
   < $30,000 321 40.1 1861 48.1 1167 44.2 138 44.8 3487 45.8  
  Don’t know 461 57.6 1538 39.8 925 35.1 111 36.0 3035 39.9  
Place of birth (n = 8310) < 0.001
  Not US born 309 34.7 2400 57.0 2096 72.8 270 81.3 5075 61.1  
  US born 581 65.3 1809 43.0 783 27.2 62 18.7 3235 38.9  
Biomedical
Body Mass Index (n = 7930) < 0.001
   < 19 97 11.3 324 8.1 109 3.9 6 1.9 536 6.8  
  19–24 467 54.4 1899 47.5 1147 41.5 118 37.9 3631 45.8  
  25–29 197 22.9 1003 25.1 853 30.9 103 33.1 2156 27.2  
   ≥ 30 98 11.4 770 19.3 655 23.7 84 27.0 1607 20.3  
Hypertensive disorders of pregnancy (n = 8498) < 0.001
  No 810 89.3 3830 89.1 2519 85.2 272 80.7 7431 87.4  
  Yes 97 10.7 467 10.9 438 14.8 65 19.3 1067 12.6  
Pregestational/gestational diabetes (n = 8500) < 0.001
  No 876 96.7 3957 92.1 2524 85.3 260 77.2 7617 89.6  
  Yes 30 3.3 340 7.9 436 14.7 77 22.8 883 10.4  
Behavioral
Father of baby support (n = 7829) < 0.001
  None/Little 201 24.3 634 16.1 383 14.0 55 17.6 1273 16.3  
  Some 278 33.6 1474 37.3 993 36.3 126 40.4 2871 36.7  
  Excellent 349 42.1 1842 46.6 1363 49.8 131 42.0 3685 47.1  
Family support (n = 7917) 0.014
  None/Little 47 5.6 301 7.5 215 7.7 30 9.3 593 7.5  
  Some 368 44.2 1786 44.8 1225 44.1 167 51.9 3546 44.8  
  Excellent 418 50.2 1900 47.7 1335 48.1 125 38.8 3778 47.7  
Major stressful events in pregnancy 0.030
  No 663 75.8 3136 75.5 2262 79.1 256 79.3 6317 76.9  
  Yes 212 24.2 1017 24.5 598 20.9 67 20.7 1894 23.1  
Smoking cigarettes (n = 8441) < 0.001
  Never 717 79.3 3321 77.8 2478 84.4 289 87.0 6805 80.6  
  Ever 187 20.7 949 22.2 457 15.6 43 13.0 1636 19.4  
Drinking alcohol (n = 8201) 0.606
  Never 798 91.3 3747 90.6 2630 91.5 290 90.6 7465 91.0  
  Ever 76 8.7 387 9.4 243 8.5 30 9.4 736 9.0  
Multivitamin supplement intake at least 3 times a week throughout pregnancy (n = 7496) < 0.001
  No 273 34.3 1050 27.7 587 22.4 71 24.5 1981 26.4  
  Yes 524 65.7 2742 72.3 2030 77.6 219 75.5 5515 73.6  
  1. a p-value from chi square tests of association; b Maternal self-report as Black, African American, Haitian or Cape Verdian;c receipt of public assistance including: WIC (Women Infants and Children), Food Stamps, AFDC (Aid to Families with Dependent Children), Housing assistance or Fuel assistance