Table 1.
Characteristics of 83,454 women according to quintiles of total PM2.5 concentrations over the first trimester (0–13 weeks of gestation) in 23 Tokyo wards, from 2013 to 2015.
| Quintile | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 (lowest) | 2 | 3 | 4 | 5 (highest) | ||||||
| Variables | n | % | n | % | n | % | n | % | n | % |
| Total PM2.5, median (interquartile range) (μg/m3) | 14.0 (13.1–14.3) | 15.2 (14.9–15.5) | 16.1 (15.8–16.4) | 17.8 (17.5–18.5) | 21.3 (20.5–21.7) | |||||
| No. of women | 16,616 | 16,736 | 16,678 | 16,714 | 16,710 | |||||
| Maternal age at delivery (years) | ||||||||||
| <25 | 680 | 4.1 | 661 | 4.0 | 661 | 4.0 | 594 | 3.6 | 638 | 3.8 |
| 25–29 | 2707 | 16.3 | 2691 | 16.1 | 2762 | 16.6 | 2723 | 16.3 | 2631 | 15.8 |
| 30–34 | 5723 | 34.4 | 5697 | 34.0 | 5782 | 34.7 | 5699 | 34.1 | 5681 | 34.0 |
| ≥35 | 7506 | 45.2 | 7687 | 45.9 | 7473 | 44.8 | 7698 | 46.1 | 7760 | 46.4 |
| Parity | ||||||||||
| 0 | 9918 | 59.7 | 10,178 | 60.8 | 10,060 | 60.3 | 10,020 | 60.0 | 10,185 | 61.0 |
| 1 | 5285 | 31.8 | 5158 | 30.8 | 5190 | 31.1 | 5222 | 31.2 | 5064 | 30.3 |
| ≥2 | 1413 | 8.5 | 1400 | 8.4 | 1428 | 8.6 | 1472 | 8.8 | 1461 | 8.7 |
| Smoking habits | ||||||||||
| No | 12,757 | 95.1 | 13,192 | 96.9 | 13,109 | 97.1 | 13,443 | 97.2 | 13,312 | 95.7 |
| Yes | 651 | 4.9 | 416 | 3.1 | 390 | 2.9 | 393 | 2.8 | 592 | 4.3 |
| Alcohol drinking | ||||||||||
| No | 11,676 | 94.4 | 11,693 | 96.5 | 11,642 | 96.5 | 11,815 | 97.1 | 11,311 | 95.6 |
| Yes | 688 | 5.6 | 425 | 3.5 | 429 | 3.6 | 355 | 2.9 | 525 | 4.4 |
| Prepregnancy body mass index (kg/m2) | ||||||||||
| <18.5 | 2768 | 19.5 | 2774 | 19.5 | 2792 | 19.7 | 2678 | 18.9 | 2794 | 19.9 |
| 18.5–24.9 | 10,352 | 72.9 | 10,412 | 73.3 | 10,341 | 73.1 | 10,412 | 73.7 | 10,235 | 72.7 |
| ≥25.0 | 1082 | 7.6 | 1015 | 7.2 | 1015 | 7.2 | 1046 | 7.4 | 1049 | 7.5 |
| Current history of diabetes/gestational diabetes | ||||||||||
| No | 15,750 | 94.8 | 15,924 | 95.2 | 15,809 | 94.8 | 15,792 | 94.5 | 15,850 | 94.9 |
| Yes | 866 | 5.2 | 812 | 4.9 | 869 | 5.2 | 922 | 5.5 | 860 | 5.2 |
| Infertility treatment | ||||||||||
| No | 13,881 | 83.5 | 14,131 | 84.4 | 14,179 | 85.0 | 13,965 | 83.6 | 13,998 | 83.8 |
| Ovarian stimulation/artificial insemination by sperm from husband | 1047 | 6.3 | 1028 | 6.1 | 952 | 5.7 | 1149 | 6.9 | 1165 | 7.0 |
| Assisted reproductive technology | 1688 | 10.2 | 1577 | 9.4 | 1547 | 9.3 | 1600 | 9.6 | 1547 | 9.3 |
| Past history of complications | ||||||||||
| Foetal growth restriction | 54 | 0.3 | 62 | 0.4 | 79 | 0.5 | 80 | 0.5 | 72 | 0.4 |
| Preeclampsia | 29 | 0.2 | 19 | 0.1 | 22 | 0.1 | 33 | 0.2 | 28 | 0.2 |
| Placental abruption | 38 | 0.2 | 36 | 0.2 | 37 | 0.2 | 41 | 0.3 | 42 | 0.3 |
| Stillbirth | 83 | 0.5 | 96 | 0.6 | 86 | 0.5 | 101 | 0.6 | 83 | 0.5 |
| Placenta-mediated pregnancy complications as a composite outcome | 1669 | 10.0 | 1792 | 10.7 | 1761 | 10.6 | 1783 | 10.7 | 1658 | 9.9 |
| Small for gestational age | 1253 | 7.6 | 1368 | 8.2 | 1343 | 8.1 | 1371 | 8.2 | 1271 | 7.6 |
| Preeclampsia | 213 | 1.3 | 222 | 1.3 | 215 | 1.3 | 234 | 1.4 | 220 | 1.3 |
| Placental abruption | 263 | 1.6 | 286 | 1.7 | 272 | 1.6 | 253 | 1.5 | 234 | 1.4 |
| Stillbirth | 77 | 0.5 | 53 | 0.3 | 65 | 0.4 | 67 | 0.4 | 61 | 0.4 |