Table 1.
Characteristics of 1790 women who conceived by ART and 3400 women who conceived spontaneously.
| Characteristicsa | ART-conception group (N = 1790) | Spontaneous-conception group (N = 3400) |
|---|---|---|
| Maternal age, year, No. (%) | ||
| <35 | 1447 (80•8) | 2952 (86•8) |
| ≥35 | 343 (19•2) | 448 (13•2) |
| Parity, No. (%) | ||
| Nulliparous | 1615 (90•2) | 2254 (66•3) |
| Multiparous | 175 (9•8) | 1145 (33•7) |
| Plurality, No. (%) | ||
| Singleton | 1349 (75•4) | 3367 (99•0) |
| Twins | 441 (24•6) | 33 (1•0) |
| Maternal pre-pregnancy BMI, kg/m2, No. (%) | ||
| <18•5 | 148 (8•3) | 465 (13•7) |
| 18•5–23•9 | 1185 (66•2) | 2284 (67•2) |
| 24–27•9 | 360 (20•1) | 411 (12•1) |
| ≥28 | 97 (5•4) | 87 (2•6) |
| Household income, CNY, No. (%) | ||
| <50,000 | 107 (6•0) | 135 (4•0) |
| 50,000–100,000 | 564 (31•5) | 638 (18•8) |
| 100,000–200,000 | 655 (36•6) | 1482 (43•6) |
| ≥200,000 | 464 (25•9) | 1110 (32•6) |
| Maternal education, year, No. (%) | ||
| <12 | 526 (29•4) | 335 (9•9) |
| ≥12 | 1264 (70•6) | 2937 (86•4) |
| Tobacco use during pregnancy, No. (%) | 1 (0•1) | 12 (0•4) |
| Alcohol intake during pregnancy, No. (%) | 5 (0•3) | 59 (1•7) |
| Diseases during pregnancy | ||
| Diabetes, No. (%)b | 502 (28•0) | 781 (23•0) |
| Hypertension, No. (%)c | 172 (9•6) | 97 (2•9) |
Abbreviation: ART, assisted reproductive technology; BMI, body mass index; CNY, China yuan.
a Missing data less than 5% for parity, maternal pre-pregnancy BMI, household income, maternal education, tobacco use during pregnancy, alcohol intake during pregnancy, diabetes and hypertension during pregnancy. No missing for maternal age and plurality.
b Includes chronic and gestational diabetes.
c Includes chronic and pregnancy-induced hypertension.