Table 5.
Pregnancy outcomes of triplets or twins reduced to singletons versus primary singletons.
| Primary singletons(n=6853) | Triplets/twins reduced to singletons (n=171) | Unadjusted P Value | Unadjusted OR (95%CI) | Adjusted P Value | Adjusted OR (95%CI) | |
|---|---|---|---|---|---|---|
| GA at delivery | 39.00 (38.0-40.0) | 38.93 (37.71-39.57) | 0.830 | – | 0.155 | – |
| Delivery<32weeks | 65 (0.9) | 6 (3.5) | 0.004 | 3.80 (1.62-8.89) | 0.002 | 1.25 (1.08-1.44) |
| Delivery<34weeks | 119 (1.7) | 9 (5.3) | 0.002 | 3.14 (1.57-6.30) | 0.001 | 1.22 (1.09-1.37) |
| Delivery<37weeks | 500 (7.3) | 27 (15.8) | <0.001 | 2.38 (1.56-3.63) | <0.001 | 1.51 (1.07-1.24) |
| Pregnancy loss <24weeks | 371 (5.4) | 9 (5.3) | 0.932 | 0.97 (0.49-1.92) | 0.671 | 0.98 (0.87-1.09) |
| Live birth | 6450 (94.1) | 162 (94.7) | 0.734 | 1.13 (0.57-2.22) | 0.496 | 1.04 (0.93-1.17) |
| Caesarean section | 4871/6463 (75.4) | 120/162 (74.1) | 0.706 | 0.93 (0.65-1.33) | 0.325 | 0.97 (0.91-1.03) |
| Birth weight (g) | 3340 (3038.73-3650) | 3055 (2750-3312.50) | <0.001 | – | <0.001 | – |
| LBW | 295 (4.3) | 21 (12.3) | <0.001 | 3.11 (1.94-4.99) | <0.001 | 1.21 (1.11-1.30) |
| VLBW | 29 (0.4) | 4 (2.3) | 0.008 | 5.64 (1.96-16.21) | 0.002 | 1.32 (1.10-1.58) |
| SGA | 451 (6.6) | 25 (14.6) | <0.001 | 2.43 (1.57-3.76) | <0.001 | 1.17 (1.09-1.26) |
Data are presented as median (IQR) or number (%). Mann–Whitney U tests and Chi-square tests or Fisher’s exact test were used for unadjusted analysis. Logistic regression and linear regression were used for adjusting certain confounders, including maternal age at conception, maternal BMI before pregnancy, type of infertility, ART methods, embryo transplantation, source of semen.
GA, gestational age; LBW, low birth weight; VLBW, very low birth weight; SGA, small for gestational age; OR, odds ratio; CI, confidence interval.