Demographic and obstetrical data of the participants
| Group A n=72 | Group B n=72 | Group C n=73 | P value | |
| Maternal age, years | 30.8±6.5 | 29.7±6.4 | 31.1±5.7 | 0.437 |
| Maternal age >35 years | 14 (19.4) | 16 (22.2) | 17 (23.3) | 0.163 |
| Ethnicity | ||||
| Han | 69 (95.8) | 68 (94.4) | 71 (97.3) | 0.532 |
| Others | 3 (4.2) | 4 (5.6) | 2 (2.7) | 0.613 |
| Pregestational body mass index (kg/m2) | 26.5 (4.3) | 27.8 (4.7) | 27.0 (5.0) | 0.559 |
| Cigarette smoker | 9 (12.5) | 10 (13.9) | 7 (9.5) | 0.370 |
| Primiparous (first birth) | 8 (11.1) | 5 (6.9) | 7 (9.6) | 0.421 |
| Anti-factor Xa level | 2.4±0.6 | 2.3±0.5 | 2.1±0.8 | 0.392 |
Group A: fixed dose group; group B: weight group; group C: anti-FXa+weight group.
FXa, factor Xa.