Subjects | 637 816 | 45 900 | |
Sociodemographic factors | | | |
Sex | | | |
Male | 318 360 (49.9) | 26 806 (58.4) | <0.001 |
Female | 319 456 (50.1) | 19 094 (41.6) | |
Missing | 0 | 0 | |
Deprivation quintile | | | |
1 (most deprived) | 141 585 (22.2) | 12 357 (26.9) | <0.001 |
2 | 126 279 (19.8) | 9941 (21.7) | |
3 | 122 827 (19.3) | 8917 (19.4) | |
4 | 126 335 (19.8) | 7985 (17.4) | |
5 (least deprived) | 120 288 (18.9) | 6667 (14.5) | |
Missing | 502 | 33 | |
Ethnic group | | | |
White | 606 601 (96.3) | 43 388 (95.5) | <0.001 |
Asian | 14 222 (2.3) | 1364 (3.0) | |
Black | 1634 (0.3) | 126 (0.3) | |
Mixed | 5471 (0.9) | 439 (1.0) | |
Other | 1732 (0.3) | 125 (0.3) | |
Missing | 8156 | 458 | |
Maternity factors | | | |
Maternal age years | | | |
≤24 | 171 602 (26.9) | 13 868 (30.2) | <0.001 |
25–29 | 187 171 (29.4) | 13 516 (29.5) | |
30–34 | 182 432 (28.6) | 12 209 (26.6) | |
≥35 | 96 600 (15.2) | 6307 (13.7) | |
Missing | 11 | 0 | |
Maternal smoking | | | |
No | 411 276 (72.8) | 28 269 (69.2) | <0.001 |
Yes | 153 337 (27.2) | 12 595 (30.8) | |
Missing | 73 203 | 5036 | |
Parity | | | |
0 | 284 289 (44.8) | 21 760 (47.7) | <0.001 |
1 | 221 459 (34.9) | 15 205 (33.3) | |
>1 | 128 980 (20.3) | 8673 (19.0) | |
Missing | 3088 | 262 | |
Mode of delivery | | | |
Spontaneous vaginal delivery | 552 730 (67.8) | 29 750 (62.4) | <0.001 |
Assisted vaginal | 75 713 (11.9) | 5587 (2.4) | |
Breech vaginal | 1825 (0.3) | 154 (12.2) | |
Elective Caesarean section | 48 267 (7.7) | 3700 (0.3) | |
Emergency Caesarean section | 79 325 (12.4) | 6700 (8.1) | |
Other | 141 (0.0) | 9 (0.0) | |
Missing | 2 | 0 | |
Gestation weeks | | | |
<24 | 17 (0.0) | 3 (0.0) | <0.001 |
24–27 | 753 (0.1) | 178 (0.4) | |
28–32 | 5338 (0.8) | 719 (1.6) | |
33–36 | 28 351 (4.5) | 2836 (6.2) | |
37 | 30 587 (4.8) | 2613 (5.7) | |
38 | 79 248 (12.4) | 6058 (13.2) | |
39 | 132 322 (20.8) | 9448 (20.6) | |
40 | 193 364 (30.3) | 13 103 (28.6) | |
41 | 143 715 (22.6) | 9451 (20.6) | |
42 | 22 979 (3.6) | 1416 (3.1) | |
43 | 542 (0.1) | 32 (0.1) | |
>43 | 120 (0.0) | 9 (0.0) | |
Missing | 480 | 34 | |
Sex-gestation-specific birthweight centile | | | |
1–3 | 25 763 (4.0) | 2153 (4.7) | <0.001 |
4–10 | 56 669 (8.9) | 4308 (9.4) | |
11–20 | 75 633 (11.9) | 5582 (12.2) | |
21–80 | 375 540 (59.0) | 26 539 (57.9) | |
81–90 | 54 540 (8.6) | 3758 (8.2) | |
91–97 | 34 407 (5.4) | 2490 (5.4) | |
98–100 | 14 266 (2.2) | 1000 (2.2) | |
Missing | 810 | 70 | |
5-min Apgar score | | | |
1–3 | 3044 (0.5) | 264 (0.6) | <0.001 |
4–6 | 5864 (0.9) | 565 (1.2) | |
7–10 | 622 502 (98.6) | 44 568 (98.2) | |
Missing | 6406 | 503 | |