Table 1.
Baseline characteristics of the study participants.
| Characteristics | Total (n = 1546) | Prepregnancy BMI | P | |||
|---|---|---|---|---|---|---|
| Underweight (n = 154) | Normal (n = 1049) | Overweight (n = 238) | Obese (n = 105) | |||
| Age, years (mean ± SD) | 30.77 ± 3.30 | 30.03 ± 2.90 | 30.55 ± 3.11 | 31.55 ± 3.69 | 31.08 ± 3.57 | <0.001 |
| History of pregnancy, n (%) | 0.240 | |||||
| Nulliparous | 125 (8.09) | 17 (11.04) | 83 (7.91) | 14 (5.88) | 11 (10.48) | |
| Yes | 1421 (91.91) | 137 (88.96) | 966 (92.09) | 224 (94.12) | 94 (89.52) | |
| Conception method, n (%) | <0.001 | |||||
| ART | 130 (8.46) | 7 (4.61) | 72 (6.90) | 32 (13.50) | 19 (18.27) | |
| Spontaneous pregnancy | 1407 (91.54) | 145 (95.39) | 972 (93.10) | 205 (86.50) | 85 (81.73) | |
| Number of pregnancies, n (%) | 0.291 | |||||
| Single | 1499 (97.27) | 152 (99.35) | 1016 (97.13) | 229 (96.22) | 102 (98.08) | |
| Multiple | 42 (2.73) | 1 (0.65) | 30 (2.87) | 9 (3.78) | 2 (1.92) | |
Note: prepregnancy BMI groups were defined underweight < 18.5 kg/m2, normal 18.5-23.9 kg/m2, overweight 24-27.9 kg/m2, and obese ≥ 28 kg/m2. P values represent the significance in the difference of the variable distribution among underweight, normal, overweight, and obese groups, with P < 0.05 as statistically significant difference. Abbreviations: SD: standard deviation; ART: assisted reproductive technology.