Table 1 Characteristics of twin pregnancies by maternal pre-pregnancy BMI classification and by gestational weight gain according to Institute of Medicine Guidelines
Characteristics | All participants (n = 645) | Weight gain within IOM guideline (n = 267) | Weight gain below IOM guideline (n = 97) | Weight gain above IOM guideline (n = 281) | P-value |
|---|---|---|---|---|---|
Maternal age, year | 32.1 ± 4.3 | 32.7 ± 4.4 | 32.0 ± 4.3 | 31.5 ± 4.2 | 0.007 |
Maternal BMI classification | |||||
 Normal | 475 (73.64) | 190 (71.16) | 69 (71.13) | 216 (76.87) | 0.506 |
 Overweight | 130 (20.16) | 58 (21.72) | 23 (23.71) | 49 (17.44) |  |
 Obesity | 40 (6.2) | 19 (7.12) | 5 (5.15) | 16 (5.69) |  |
Nulliparity | 415 (64.34) | 159 (59.55) | 66 (68.04) | 190 (67.62) | 0.102 |
Chorionic hypertension | 2 (0.31) | 1 (0.37) | 1 (1.03) | 0 (0) | 0.147 |
Pre-existing diabetes mellitus | 11 (1.78) | 4 (1.57) | 4 (4.26) | 3 (1.12) | 0.131 |
College degreea | 283 (49.13) | 126 (53.85) | 44 (51.76) | 113 (43.97) | 0.080 |
Use of ART | 486 (75.35) | 203 (76.03) | 74 (76.29) | 209 (74.38) | 0.880 |
Prior cesarean section | 99 (15.35) | 39 (14.61) | 13 (13.4) | 47 (16.73) | 0.668 |
Prior spontaneous abortion | 131 (20.31) | 65 (24.34) | 15 (15.46) | 51 (18.15) | 0.086 |
Prior induced abortion | 137 (21.24) | 58 (21.72) | 21 (21.65) | 58 (20.64) | 0.948 |
MCDA twin gestation | 97 (15.04) | 35 (13.11) | 14 (14.43) | 48 (17.08) | 0.422 |
Gestational diabetes mellitus | 154 (23.88) | 69 (25.84) | 40 (41.24) | 45 (16.01) | < 0.001 |
Cesarean section | 635 (98.45) | 263 (98.50) | 96 (98.97) | 276 (98.22) | 1.000 |