Distribution of maternal characteristics and complications by anaemia status
| Characteristics | Total N (%) | Maternal haemoglobin, N (%) | |||
| Normal ≥110 g/L | Mild 100–109 g/L | Moderate 70–99 g/L | Severe <70 g/L | ||
| Deliveries | 34 087 | 28 515 (83.7) | 3703 (10.9) | 1769 (5.2) | 100 (0.3) |
| Maternal age (years) | |||||
| <35 | 26 433 (77.5) | 22 082 (77.4) | 2890 (78.0) | 1382 (78.1) | 79 (79.0) |
| ≥35 | 7654 (22.5) | 6433 (22.6) | 813 (22.0) | 387 (21.9) | 21 (21.0) |
| Maternal BMI | |||||
| <18.5 | 4920 (14.4) | 3978 (14.0) | 574 (15.5) | 336 (19.0) | 32 (32.0) |
| 18.5–23.9 | 23 913 (70.2) | 20 123 (70.6) | 2547 (68.8) | 1184 (76.9) | 59 (59.0) |
| 24–27.9 | 4329 (12.7) | 3653 (12.8) | 472 (12.7) | 195 (11.0) | 9 (9.0) |
| ≥28 | 925 (2.7) | 761 (2.7) | 110 (3.0) | 54 (3.1) | 0 (0.0) |
| Residence | |||||
| Urban | 21 062 (61.8) | 17 672 (62.0) | 2253 (60.8) | 1082 (61.2) | 55 (55.0) |
| Rural | 13 025 (38.2) | 10 843 (38.0) | 1450 (39.2) | 687 (38.8) | 45 (45.0) |
| Education level | |||||
| Junior high school or below | 2547 (7.5) | 1705 (6.0) | 516 (13.9) | 299 (16.9) | 27 (27.0) |
| Senior middle school | 9684 (28.4) | 7842 (27.5) | 1218 (32.9) | 594 (33.6) | 30 (30.0) |
| College | 15 588 (45.7) | 13 618 (47.8) | 1346 (36.3) | 586 (33.1) | 38 (38.0) |
| Master or above | 6268 (18.4) | 5350 (18.8) | 623 (18.8) | 290 (16.4) | 5 (5.0) |
| Ethnicity | |||||
| Han | 33 639 (98.7) | 28 129 (98.6) | 3686 (99.5) | 1730 (97.8) | 94 (94.0) |
| Minority | 448 (1.3) | 386 (1.4) | 17 (0.5) | 39 (2.2) | 6 (6.0) |
| Parity | |||||
| 0 | 10 488 (30.8) | 9274 (32.5) | 813 (22.0) | 369 (20.9) | 32 (32.0) |
| 1–3 | 20 189 (59.2) | 16 601 (58.2) | 2362 (62.8) | 1168 (66.0) | 58 (58.0) |
| ≥4 | 3410 (10.0) | 2640 (9.3) | 528 (14.3) | 232 (13.1) | 10 (10.0) |
| Per caput monthly family income | |||||
| ≤¥2500 | 5875 (17.2) | 4916 (17.2) | 622 (16.8) | 322 (18.2) | 15 (15.0) |
| ¥2500 to ¥5000 | 18 206 (53.4) | 15 225 (53.4) | 1980 (53.5) | 944 (53.4) | 57 (57.0) |
| >¥5000 | 10 006 (29.4) | 8374 (29.4) | 1101 (29.7) | 503 (28.4) | 28 (28.0) |
| Folic acid use* | 32 540 (95.5) | 27 272 (95.6) | 3490 (94.2) | 1687 (95.4) | 91 (91.0) |
| Gestational diabetes mellitus | 5424 (15.9) | 4689 (16.4) | 485 (13.1) | 250 (14.1) | 0 (0.0) |
| Gestational hypertension | 1246 (3.7) | 1012 (3.5) | 161 (4.3) | 68 (3.8) | 5 (5.0) |
| Hyperlipidaemia | 375 (1.1) | 312 (1.1) | 35 (0.9) | 28 (1.6) | 0 (0.0) |
| Hyperthyroidism | 636 (1.9) | 542 (1.9) | 71 (1.9) | 23 (1.3) | 0 (0.0) |
| Placenta previa | 606 (1.8) | 492 (1.7) | 70 (1.9) | 42 (2.4) | 2 (2.0) |
*Folic acid use before or during pregnancy.
BMI, body mass index.