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Table 2 Maternal characteristics of spontaneous/pPROM and provider-initiated preterm births as compared to term births

From: Prevalence and risk factors related to preterm birth in Brazil

  Spontaneous/pPROM preterm births P-value of Spontaneous vs. Term Provider-initiated preterm births P-value of Provider-initiated vs. Term Term births (37–41 weeks)
n % n % n %
Total 1,681 100.0   1,090 100.0   20,677 100.0
Level 1 - Sociodemographic characteristics
 Childbirth healthcare
  Public 1,439 85.6 0.065 758 69.5 <0.001 16,445 79.5
  Private 241 14.3 332 30.4 4,232 20.5
 Age (n = 1,678, 1,087 and 20,674)
  12 to 19 462 27.5 <0.001 145 13.4 <0.001 3,840 18.6
  20 to 34 1,051 62.6 754 69.4 14,692 71.0
   ≥ 35 165 9.8 188 17.3 2,142 10.4
 Skin color (n = 1,681, 1,087 and 20,673)
  White 522 31.1 0.312 414 38.1 0.084 7,075 34.2
  Black 155 9.2 70 6.5 1,765 8.5
  brown 1,003 59.7 603 55.5 11,833 57.3
 Marital status (n = 1,678, 1,087 and 20,659)
  Live with a partner 1,356 80.4 0.701 927 85.3 0.024 16,818 81.4
  Do not live with a partner 321 19.0 160 14.7 3,841 18.6
 Years of schooling (n = 1,672, 1,083 and 20,582)
   ≤ 7 544 32.5 <0.001 230 21.2 <0.001 5,349 26.0
  8 to 10 469 28.0 222 20.5 5,265 25.6
  11 to 14 562 33.6 475 43.9 8,097 39.3
   ≥ 15 97 5.8 156 14.4 1,871 9.1
Level 2 - Obstetric history
 Previous births
  0 872 51.9 <0.001 556 51.0 0.032 9,565 46.3
  1 to 2 611 36.4 416 38.1 9,029 43.6
   ≥ 3 197 11.7 118 10.9 2,083 10.1
 Previous abortiona (n = 918, 626 and 12,166)
  No 635 69.2 0.206 394 63.0 0.005 8,710 71.6
  Yes 283 30.8 232 37.0 3,456 28.4
 Previous stillbirth or neonatal deathb (n = 810, 534 and 11,113)
  No 729 90.1 0.003 468 87.6 <0.001 10,385 93.4
  Yes 80 9.9 66 12.4 728 6.6
 Previous preterm birthb (n = 810, 534 and 11,113)
  No 584 72.1 <0.001 393 73.7 <0.001 9,992 89.9
  Yes 226 27.9 140 26.3 1,121 10.1
  Previous caesarean sectionb (n = 810, 534 and 11,113)
  No 587 72.5 <0.001 241 45.0 <0.001 6,585 59.2
  1 171 21.2 202 37.8 3,465 31.2
   ≥ 2 51 6.3 91 17.1 1,063 9.6
Level 3 - Maternal/fetal conditions during pregnancy
 Adequacy of antenatal care (n = 1,621, 1,061 and 20,175)
  Adequate 952 58.7 <0.001 791 74.5 <0.001 13,327 66.1
  Inadequate or partially adequate 669 41.3 270 25.5 6,848 33.9
 Pre-pregnancy weight status (BMI) (n = 1,666, 1,078 and 20,604)
  Urderweight (≤18,5) 147 8.8 0.100 75 7.0 <0.001 1,656 8.0
  Normal weight (18,5-24,9) 1,066 64.0 593 55.0 12,719 61.8
  Overweight (25–29,9) 342 20.5 259 24.0 4,326 21.0
  Obese (≥30) 112 6.7 152 14.1 1,903 9.2
 Smoking during pregnancy
  No 1,553 92.4 0.069 1,050 96.3 0.076 19,484 94.3
  Yes, less than 10 cigarettes/day 69 4.1 29 2.6 670 3.2
  Yes, 10 or more cigarettes/day 58 3.5 12 1.1 523 2.5
 Type of pregnancy
  Single 1,483 88.2 <0.001 924 84.7 <0.001 20,476 99.0
  Multiple 198 11.8 166 15.3 201 1.0
 Obstetric risk
  Any below 329 19.6 0.104 720 66.0 <0.001 4,532 21.9
   Hypertensive disordersc 130 7.8 0.112 460 42.2 <0.001 1,992 9.6
   Eclampsia 3 0.2 0.063 41 3.8 <0.001 88 0.4
   Preexisting Diabetes 16 1.0 0.857 39 3.6 <0.001 194 0.9
   Gestational Diabetes 113 6.7 0.115 168 15.4 <0.001 1,657 8.0
   Severe chronic diseasesd 12 0.7 0.925 26 2.4 <0.001 162 0.8
   Infection at hospital admission for birth 19 1.2 <0.001 13 1.1 <0.001 49 0.2
   Abruptio placentae 33 2.0 0.005 71 6.5 <0.001 187 0.9
   Placental praevia 8 0.5 0.423 25 2.3 <0.001 77 0.4
   IUGR 51 3.1 0.020 217 19.9 <0.001 982 4.7
   Major newborn malformatione 10 0.6 0.025 10 0.9 <0.001 31 0.1
  1. aExcluded primigravida women from the analysis
  2. bExcluded nuliparous women from the analysis
  3. cChronic hypertension, pre-eclampsia and HELLP syndrome
  4. dChronic renal diseases, chronic cardiac diseases and auto-immune diseases
  5. eIncluded anencephaly, hidrocephaly, spina bifida, gastrosquisis and other abdominal wall defects, cardiac malformations and multiple malformations