Composition ratio of different β-hCG levels in each group (N (%))
| Group | N | β-hCG (mIU/mL) | N (%) | |
| ≤5.34 | 5.35–17.95 | >17.95 | ||
| Single OP | 515 | 96 (18.6%) | 356 (69.1%) | 63 (12.2%) |
| Twin OP | 238 | 3 (1.2%) | 40 (16.8%) | 195 (81.9%) |
| AP | 308 | 220 (71.4%) | 67 (21.8%) | 21 (6.8%) |
AP, adverse pregnancy; β-hCG, plasma human chorionic gonadotropin; OP, ongoing pregnancy.