Table 3.
Preterm birth in twin pregnancies after assisted conception compared with matched controls (natural conception)
| Study | No (%) assisted | No (%) natural | Relative risk (95% CI) |
|---|---|---|---|
| Very preterm (<32 weeks) | |||
| Dhont et al1* | 173/2482 (7.0) | 178/2482 (7.2) | 0.97 (0.79 to 1.19)* |
| Dhont et al9 | 16/230 (7.0) | 12/230 (5.2) | 1.33 (0.65 to 2.76) |
| Koivurova et al19† | 2/103 (1.9) | 11/103 (10.7) | 0.18 (0.04 to 0.80)† |
| Total | 191/2815 (6.8) | 201/2815 (7.1) | 0.95 (0.78 to 1.15) |
| Preterm (<37 weeks) | |||
| Dhont et al1* | 1227/2482 (49.4) | 1184/2482 (47.7) | 1.04 (0.98 to 1.10)* |
| Dhont et al9 | 120/230 (52.2) | 98/230 (42.6) | 1.22 (1.01 to 1.49) |
| Isaksson et al10 | 14/40 (35.0) | 82/200 (41.0) | 0.85 (0.54 to 1.34) |
| Koivurova et al19† | 45/103 (43.7) | 45/103 (43.7) | 1.00 (0.73 to 1.36)† |
| Koudstaal et al13 | 98/192 (51.0) | 80/192 (41.7) | 1.23 (0.99 to 1.52) |
| Moise et al11 | 24/40 (60.0) | 16/80 (20.0) | 3.00 (1.81 to 4.98) |
| Petersen et al22 | 6/32 (18.8) | 12/32 (37.5) | 0.50 (0.21 to 1.17) |
| Tallo et al12† | 40/68 (58.8) | 25/68 (36.8) | 1.60 (1.11 to 2.32)† |
| Tan et al4 | 146/250 (58.4) | 22/42 (52.4) | 1.11 (0.82 to 1.52) |
| Total | 1720/3437 (50.0) | 1564/3429 (45.6) | 1.07 (1.02 to 1.13) |
*
Based on additional data obtained from the authors.
†
Surviving infants only.