Table 1 Descriptive statistics for study participants from the MoBa cohort: N (%) or mean ± standard deviation
From: Association between pregnancy exposure to air pollution and birth weight in selected areas of Norway
Oslo (N = 4669) | Akershus (N = 7554) | Bergen (N = 3869) | Hordaland (N = 1441) | Total (N = 17533) | |
|---|---|---|---|---|---|
Birth weighta, g | 3539 ± 545 | 3617 ± 558 | 3592 ± 550 | 3628 ± 553 | 3592 ± 554 |
Low birth weight | 153 (3.3) | 192 (2.5) | 107 (2.8) | 39 (2.7) | 491 (2.8) |
Missing | 7 (0.1) | 3 (0.1) | 10 (0.1) | ||
Gestational age, weeks | 39.7 ± 1.9 | 39.8 ± 1.9 | 39.8 ± 1.9 | 39.7 ± 1.9 | 39.8 ± 1.9 |
Preterm delivery | 241 (5.2) | 340 (4.5) | 170 (4.4) | 68 (4.7) | 819 (4.7) |
Women who changed address during pregnancy | 629 (13.5) | 1023 (13.5) | 513 (13.3) | 171 (11.9) | 2336 (13.3) |
Parity | |||||
0 | 2819 (60.4) | 3032 (40.1) | 1930 (49.9) | 529 (36.7) | 8310 (47.4) |
1 | 1424 (30.5) | 3052 (40.4) | 1314 (34.0) | 538 (37.3) | 6328 (36.1) |
≥ 2 | 426 (9.1) | 1470 (19.5) | 625 (16.2) | 374 (26.0) | 2895 (16.5) |
Birth weight by parity, g | |||||
0 | 3471 ± 544 | 3512 ± 547 | 3484 ± 545 | 3524 ± 547 | 3492 ± 546 |
1 | 3645 ± 522 | 3676 ± 542 | 3687 ± 502 | 3652 ± 554 | 3669 ± 531 |
≥ 2 | 3630 ± 562 | 3712 ± 579 | 3722 ± 596 | 3742 ± 533 | 3706 ± 575 |
Sex of child | |||||
Boy | 2413 (51.7) | 3808 (50.4) | 1950 (50.4) | 754 (52.3) | 8925 (50.9) |
Girl | 2256 (48.3) | 3746 (49.6) | 1919 (49.6) | 687 (47.7) | 8608 (49.1) |
Maternal age, years | 31.3 ± 4.1 | 31.4 ± 4.5 | 30.5 ± 4.6 | 29.5 ± 4.8 | 31.0 ± 4.5 |
Marital status | |||||
Married/cohabit | 4530 (97.0) | 7335 (97.1) | 3576 (92.4) | 1339 (92.9) | 16780 (95.7) |
Other | 139 (3.0) | 219 (2.9) | 293 (7.6) | 102 (7.1) | 753 (4.3) |
Maternal education | |||||
Less than high school | 140 (3.0) | 495 (6.6) | 207 (5.4) | 144 (10.0) | 986 (5.6) |
High school | 804 (17.2) | 2062 (27.3) | 842 (21.8) | 467 (32.4) | 4175 (23.8) |
Up to 4 years of college | 1734 (37.1) | 2768 (36.6) | 1455 (37.6) | 523 (36.3) | 6480 (37.0) |
More than 4 years of college (master or professional degree) | 1762 (37.7) | 1772 (23.5) | 1115 (28.8) | 218 (15.1) | 4867 (27.8) |
Missing | 229 (4.9) | 457 (6.1) | 250 (6.5) | 89 (6.2) | 1025 (5.9) |
Maternal smoking during pregnancy | 171 (3.7) | 555 (7.4) | 225 (5.8) | 134 (9.3) | 1085 (6.2) |
Missing | 221 (4.7) | 443 (5.9) | 247 (6.4) | 89 (6.2) | 1000 (5.7) |
Maternal weighta, kg | 65.3 ± 10.4 | 67.3 ± 11.4 | 66.3 ± 11.0 | 68.4 ± 11.9 | 66.7 ± 11.2 |
Maternal heighta, cm | 168.4 ± 6.1 | 168.3 ± 5.9 | 168.0 ± 5.9 | 167.9 ± 6.1 | 168.2 ± 5.9 |
Season of birth | |||||
Winter | 1042 (22.3) | 1650 (21.8) | 1015 (26.2) | 392 (27.2) | 4099 (23.4) |
Spring | 1224 (26.2) | 2052 (27.2) | 1020 (26.4) | 390 (27.1) | 4686 (26.7) |
Summer | 1292 (27.7) | 2102 (27.8) | 900 (23.3) | 336 (23.3) | 4630 (26.4) |
Autumn | 1111 (23.8) | 1750 (23.2) | 934 (24.1) | 323 (22.4) | 4118 (23.5) |
LUR modelled NO2 exposure during pregnancy, μg/m3 | 21.6 ± 4.4 | 10.3 ± 3.8 | 13.2 ± 6.2 | 6.3 ± 4.3 | 13.6 ± 6.9 |