Table 3. Twin Delivery Rates by Prepregnancy BMI Category and Use of ART.
| Prepregnancy BMI | Overall | ART | Non-ART | |||
|---|---|---|---|---|---|---|
| Total births, No. | Twin births, No. (per 1000) | Total births, No. | Twin births, No. (per 1000) | Total births, No. | Twin births, No. (per 1000) | |
| Underweight | 22 396 | 253 (11.3) | 495 | 65 (131.3) | 21 901 | 188 (8.58) |
| Normal | 231 583 | 3323 (14.4) | 6823 | 977 (143.2) | 224 760 | 2346 (10.44) |
| Overweight | 83 887 | 1340 (16.0) | 2570 | 363 (141.3) | 81 317 | 977 (12.01) |
| Obese I | 33 263 | 531 (16.0) | 1054 | 134 (127.1) | 32 209 | 397 (12.33) |
| Obese II | 13 308 | 222 (16.7) | 426 | 63 (147.9) | 12 882 | 159 (12.34) |
| Obese III | 7609 | 144 (18.9) | 155 | 23 (148.4) | 7454 | 121 (16.23) |
Abbreviations: ART, assisted reproductive technology; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared).