Table 5.
Comparison of monochorionic and dichorionic twin conceived by assisted reproduction
| Assisted conception | ||||
|---|---|---|---|---|
| Monochorionic twins (n = 29) | Dichorionic twins (n = 545) | p‐value | OR (95% CI) | |
| Maternal age, years (mean ± SD) | 33.7 ± 3.1 | 33.9 ± 4.3 | 0.673 | |
| Age ≥35 years, n (%) | 24 (41.4) | 256 (47.0) | 0.405 | |
| Parity (median, range) | 0 (0–3) | 0 (0–6) | 0.038 | |
| Nulliparous, n (%) | 23 (79.3) | 355 (65.1) | 0.027 | 0.5 (0.2–1.0) |
| Imminent preterm labor, n (%) | 4 (13.8) | 126 (23.1) | 0.098 | |
| Hypertensive disorders, n (%) | 7 (24.1) | 109 (20.0) | 0.444 | |
| Pregnancy‐induced and pre‐existing hypertension, n (%) | 3 (10.3) | 33 (6.1) | 0.189 | |
| Preeclampsia, n (%) | 4 (13.9) | 79 (14.5) | 0.882 | |
| Diabetes, n (%) | 3 (10.3) | 18 (3.3) | 0.005 | 0.2 (0.1–0.5) |
| Cesarean section, n (%) | 15 (54.4) | 261 (48.3) | 0.370 | |
| Elective CS | 7 (22.4) | 102 (18.8) | 0.495 | |
| Emergency CS | 9 (31.6) | 159 (29.4) | ||
| n = 58 fetuses | n = 1090 fetuses | |||
| Gestational age, weeks (median, range) | 36+3 (23+0–37+2) | 37+2 (22+4–41+6) | <0.001 | |
| <32 weeks, n (%) | 8 (13.8) | 73 (6.7) | 0.040 | 0.4 (0.1–1.6) |
| 32–37 weeks, n (%) | 26 (44.8) | 394 (36.1) | 0.181 | |
| ≥37 weeks, n (%) | 24 (41.4) | 622 (57.2) | 0.018 | 1.9 (1.1–3.2) |
| Birthweight, grams (mean ± SD) | 2133 ± 681 | 2475 ± 625 | <0.001 | |
| SGA, n (%) | 10 (17.2) | 169 (1.65) | 0.736 | |
| Low birthweight, n (%) | 40 (69.0) | 510 (46.8) | 0.001 | 0.5 (0.2–1.0) |
| Very low birthweight, n (%) | 11 (19.0) | 81 (7.4) | 0.002 | 0.3 (0.2–0.7) |
| Mortality | ||||
| IUFD, n (%) | 1 (1.7) | 14 (0.7) | 0.126 | |
| Early NND, n (%) | 2 (3.4) | 13 (1.2) | 0.403 | |
| Late NND, n (%) | 2 (3.4) | 1 (0.1) | <0.001 | 0.1 (0.0–0.3) |
| Neonatal morbiditya | ||||
| RDS, n (%) | 11 (19.0) | 59 (5.4) | <0.001 | 0.2 (0.1–0.5) |
| IVH, n (%) | 2 (3.4) | 21 (1.9) | 0.420 | |
| NEC, n (%) | 5 (8.6) | 8 (0.7) | <0.001 | 0.2 (0.4–1.1) |
| Sepsis, n (%) | 3 (5.2) | 40 (3.7) | 0.557 | |
| Major neonatal morbidity, n (%)a | 14 (24.1) | 94 (8.6) | <0.001 | 0.3 (0.2–0.6) |
| Admission to NICU, n (%)a | 16 (27.6) | 141 (12.9) | 0.002 | 0.8 (0.3–2.1) |
Abbreviations: CI, confidence interval; CS, cesarean section; IUFD, intrauterine fetal death; IVH, intraventricular hemorrhage; NEC, necrotizing enterocolitis; NICU, neonatal intensive care unit; NND, neonatal death; OR, odds ratio; RDS, respiratory distress syndrome; SGA, small for gestational age.
a
Excluding intrauterine fetal deaths.