From: Preterm birth and PM2.5 in Puerto Rico: evidence from the PROTECT birth cohort
Characteristic | Number of births (Number of PTBs) | Risk ratio (95% CI) | p-value |
---|---|---|---|
Age of mother (years) | Â | Â | 0.28 |
  < 25 | 539 (46) | 1.01 (0.98, 1.03) |  |
  ≥ 25 | 553 (53) | 1.01 (1.00, 1.02) |  |
Annual family income, US dollars | Â | Â | 0.36 |
 < 30,000 | 573 (62) | 1.01 (0.99, 1.03) |  |
  ≥ 30,000 | 362 (26) | 1.00 (0.99, 1.01) |  |
Infant sex | Â | Â | 0.12 |
 Male | 572 (59) | 1.00 (0.98, 1.02) |  |
 Female | 519 (40) | 1.02 (1.00, 1.04) |  |
History of adverse pregnancy outcomes | Â | Â | 0.72 |
 No | 833 (68) | 1.00 (0.98, 1.03) |  |
 Yes | 259 (31) | 1.01 (1.00, 1.02) |  |
Pre-pregnancy body mass index | Â | Â | 0.74 |
 Not obese | 853 (68) | 1.01 (1.00, 1.02) |  |
 Obese | 179 (21) | 1.00 (0.97, 1.03) |  |
Number of pregnancies | Â | Â | 0.98 |
 Only this one | 454 (39) | 1.01 (0.99, 1.02) |  |
 Have had other pregnancies | 624 (59) | 1.01 (0.99, 1.02) |  |
Education level | Â | Â | 0.30 |
  ≤ High school | 351 (47) | 1.01 (0.98, 1.04) |  |
  > High school | 724 (51) | 1.00 (0.99, 1.02) |  |
Prenatal DBP | Â | Â | 0.50 |
 Median (2.70) or less | 354 (25) | 0.83 (0.62, 1.10) |  |
 More than median | 352 (33) | 0.97 (0.77, 1.24) |  |
Prenatal DiBP | Â | Â | 0.63 |
 Median (2.68) or less | 355 (22) | 0.94 (0.77, 1.15) |  |
 More than median | 351 (36) | 0.97 (0.67, 1.39) |  |