Table 3. Pregnancy and Birth Outcomes in Double-Embryo Transfer (DET) vs Single-Embryo Transfer (SET) Pregnancies, Excluding Possible Twin Pregnancies.
| AAR, % (95% CI) | ARD, percentage points (95% CI) | RRR or OR (95% CI)a | ||
|---|---|---|---|---|
| DET | SET | |||
| Gestational hypertension (yes vs no) | 5.9 (5.2 to 6.6) | 5.8 (5.5 to 6.0) | 0.1 (−0.6 to 0.9) | 1.02 (0.89 to 1.18) |
| Preeclampsia (yes vs no) | 3.8 (3.2 to 4.4) | 3.9 (3.7 to 4.2) | −0.1 (−0.7 to 0.5) | 0.97 (0.82 to 1.15) |
| Gestational diabetes (yes vs no) | 1.9 (1.5 to 2.3) | 2.1 (2.0 to 2.3) | −0.2 (−0.7 to 0.2) | 0.90 (0.71 to 1.12) |
| Bleeding during pregnancy (yes vs no) | 4.8 (4.2 to 5.4) | 4.7 (4.4 to 4.9) | 0.1 (−0.5 to 0.8) | 1.03 (0.89 to 1.19) |
| Placental abruption (yes vs no) | 0.6 (0.4 to 0.8) | 0.6 (0.5 to 0.7) | 0.0 (−0.2 to 0.3) | 1.04 (0.69 to 1.59) |
| Prelabor rupture of membranes (yes vs no) | 2.3 (1.9 to 2.8) | 2.5 (2.3 to 2.7) | −0.1 (−0.6 to 0.4) | 0.94 (0.76 to 1.17) |
| Mode of delivery (vs unassisted vaginal) | ||||
| Instrumental vaginal | 12.6 (11.5 to 13.8) | 12.3 (11.8 to 12.7) | 0.4 (−0.9 to 1.6) | 1.04 (0.92 to 1.17) |
| Planned cesarean | 14.7 (13.6 to 15.9) | 14.1 (13.6 to 14.5) | 0.6 (−0.6 to 1.9) | 1.06 (0.95 to 1.17) |
| Emergency cesarean | 19.1 (17.8 to 20.4) | 18.6 (18.1 to 19.1) | 0.5 (−0.9 to 1.9) | 1.03 (0.94 to 1.14) |
| Induced delivery (yes vs no) | 19.5 (18.3 to 20.7) | 19.0 (18.6 to 19.5) | 0.4 (−0.9 to 1.8) | 1.03 (0.95 to 1.12) |
| Infant death within 0-27 d (yes vs no) | 0.3 (0.1 to 0.5) | 0.1 (0.1 to 0.2) | 0.2 (0.0 to 0.4) | 2.68 (1.26 to 5.70) |
| Gestational age (vs term) | ||||
| Moderately preterm (32-36 wk) | 5.2 (4.5 to 5.9) | 5.8 (5.5 to 6.1) | −0.6 (−1.4 to 0.1) | 0.89 (0.77 to 1.03) |
| Very preterm (<32 wk) | 1.4 (1.0 to 1.8) | 1.2 (1.1 to 1.4) | 0.2 (−0.2 to 0.6) | 1.14 (0.85 to 1.53) |
| Low birth weight (<2500 g vs ≥2500 g) | 4.6 (4.0 to 5.3) | 4.8 (4.6 to 5.1) | −0.2 (−0.9 to 0.5) | 0.96 (0.82 to 1.12) |
| BWGA percentile (vs 25.0-74.9 percentile) | ||||
| <10.0 | 21.6 (20.0 to 23.2) | 20.6 (20.1 to 21.2) | 0.9 (−0.8 to 2.7) | 1.06 (0.95 to 1.18) |
| 10.0-24.9 | 26.6 (25.0 to 28.3) | 25.5 (24.9 to 26.1) | 1.1 (−0.7 to 2.9) | 1.06 (0.96 to 1.16) |
| 75.0-89.9 | 17.8 (16.3 to 19.3) | 19.8 (19.3 to 20.4) | −2.0 (−3.6 to −0.4) | 0.88 (0.78 to 0.98) |
| ≥90.0 | 12.0 (10.7 to 13.2) | 14.2 (13.7 to 14.7) | −2.2 (−3.6 to −0.8) | 0.82 (0.72 to 0.93) |
| Apgar score (<7 vs ≥7) | 1.6 (1.2 to 2.0) | 1.6 (1.4 to 1.7) | 0.1 (−0.4 to 0.5) | 1.05 (0.80 to 1.37) |
| Congenital malformation (vs none) | ||||
| Any | 4.6 (4.0 to 5.3) | 4.0 (3.8 to 4.2) | 0.6 (−0.1 to 1.3) | 1.16 (0.99 to 1.37) |
| Major | 2.8 (2.3 to 3.4) | 2.3 (2.1 to 2.5) | 0.5 (0.0 to 1.1) | 1.24 (1.01 to 1.52) |
| Minor | 1.9 (1.5 to 2.3) | 1.8 (1.6 to 1.9) | 0.1 (−0.3 to 0.6) | 1.07 (0.83 to 1.37) |
| Sex of baby (boy vs girl) | 49.7 (48.2 to 51.3) | 51.7 (51.1 to 52.3) | −2.0 (−3.7 to −0.3) | 0.92 (0.86 to 0.99) |
Abbreviations: AAR, adjusted absolute risk; ARD, absolute risk difference; BWGA, birth weight for gestational age; OR, odds ratio; RRR, relative risk ratio.
a
Odds ratios for binary outcomes and RRRs for categorical outcomes, adjusted for maternal age at delivery, birth order, delivery year, maternal country of birth, previous spontaneous abortion, previous extrauterine pregnancy, and total number of stimulations.