Table 4.
Comparison of mono‐ and dichorionic twin by spontaneous conception
| Spontaneous conception | ||||
|---|---|---|---|---|
| Monochorionic twins (n = 223) | Dichorionic twins (n = 508) | p‐value | OR (95% CI) | |
| Maternal age, years (mean ± SD) | 31.4 ± 4.8 | 32.5 ± 4.5 | <0.001 | |
| Age ≥35 years, n (%) | 53 (23.7) | 176 (34.6) | <0.001 | 1.6(1.2–2.1) |
| Parity (median, range) | 0 (0–8) | 1 (0–5) | 0.548 | |
| Nulliparous, n (%) | 95 (42.7) | 214 (42.1) | 0.830 | |
| Imminent preterm labor, n (%) | 42 (18.8) | 108 (21.3) | 0.281 | |
| Hypertensive disorders, n (%) | 31 (13.9) | 87 (17.2) | 0.109 | |
| Pregnancy‐induced and pre‐existing hypertension, n (%) | 17 (7.6) | 27 (5.4) | 0.106 | |
| Preeclampsia, n (%) | 17 (7.6) | 56 (11.0) | 0.045 | 1.7 (1.1–2.5) |
| Diabetes, n (%) | 5 (2.2) | 22 (4.3) | 0.050 | 1.8 (0.9–3.7) |
| Cesarean section, n (%) | 104 (47.2) | 247 (48.9) | 0.554 | |
| Elective CS | 48 (21.7) | 89 (17.5) | 0.059 | |
| Emergency CS | 56 (25.3) | 158 (31.3) | 0.223 | |
| n = 446 fetuses | n = 1016 fetuses | |||
| Gestational age, weeks (median, range) | 36+4 (20+2–40+4) | 37+1 (23+2–41+3) | <0.001 | |
| <32 weeks, n (%) | 60 (13.4) | 122 (12.0) | 0.450 | |
| 32–37 weeks, n (%) | 212 (47.4) | 344 (33.9) | <0.001 | 0.5 (0.3–0.7) |
| ≥37 weeks, n (%) | 174 (39.1) | 550 (54.1) | <0.001 | 1.8 (1.5–2.3) |
| Birthweight, grams (mean ± SD) | 2268 ± 610 | 2471 ± 679 | <0.001 | |
| SGA, n (%) | 63 (14.1) | 166 (16.5) | 0.258 | |
| Low birthweight, n (%) | 275 (61.5) | 462 (45.5) | <0.001 | 0.7 (0.5–0.9) |
| Very low birthweight, n (%) | 53 (11.9) | 105 (10.3) | 0.388 | |
| Mortality | ||||
| IUFD, n (%) | 11 (2.5) | 10 (1.0) | 0.029 | 0.3 (0.1–0.8) |
| Early NND, n (%) | 13 (2.9) | 16 (1.6) | 0.246 | |
| Late NND, n (%) | 0 | 3 (0.3) | 0.250 | |
| Neonatal morbiditya | ||||
| RDS, n (%) | 35 (7.8) | 69 (6.8) | 0.476 | |
| IVH, n (%) | 13 (2.9) | 23 (2.3) | 0.464 | |
| NEC, n (%) | 8 (1.8) | 6 (0.6) | 0.030 | 0.4 (0.1–1.2) |
| Sepsis, n (%) | 36 (8.1) | 46 (4.5) | 0.007 | 0.6 (0.3–1.1) |
| Major neonatal morbidity, n (%)a | 64 (14.3) | 107 (10.5) | 0.038 | 0.7 (0.5–1.0) |
| Admission to NICU, n (%)a | 102 (22.8) | 151 (14.9) | <0.001 | 0.6 (0.4–0.8) |
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.