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Table 1 Cohort extraction: Baseline characteristics of the cohort

From: Outcomes of multiple gestation births compared to singleton: analysis of multicenter KID database

Characteristic Category Singletons Twins Triplets or More p-value
Gestational age < 24 weeks 20,277 (0.09%) 4816 (0.71%) 713 (2.48%)  
  24 weeks 7458 (0.03%) 1873 (0.28%) 245 (0.85%) <.0001
  25–26 weeks 18,338 (0.08%) 4694 (0.69%) 676 (2.35%)  
  27–28 weeks 26,293 (0.12%) 7876 (1.17%) 1325 (4.62%)  
  29–30 weeks 40,542 (0.18%) 13,722 (2.03%) 2526 (8.80%)  
  31–32 weeks 81,279 (0.37%) 31,474 (4.66%) 4741 (16.51%)  
  33–34 weeks 224,024 (1.01%) 77,985 (11.54%) 6888 (23.99%)  
  35–36 weeks 603,530 (2.72%) 149,048 (22.05%) 3735 (13.01%)  
  Preterm but GA Unknown 287,185 (1.30%) 65,088 (9.63%) 6312 (21.98%)  
  > 37 weeks 20,839,514 (94.09%) 319,393 (47.25%) 1554 (5.41%)  
  Total 22,148,440 (100.00%) 675,969 (100.00%) 28,716 (100.00%)  
IUGR or SGA Yes 367,274 (1.66%) 45,653 (6.75%) 1856 (6.46%) <.0001
Sex Female 10,843,182 (49.02%) 336,883 (49.89%) 14,295 (49.83%) <.0001
  Male 11,274,557 (50.98%) 338,380 (50.11%) 14,393 (50.17%)  
  Total 22,117,739 (100.00%) 675,263 (100.00%) 28,687 (100.00%)  
Race/Ethnicity White 9,579,294 (52.79%) 330,163 (59.27%) 16,247 (70.15%) <.0001
  Black 2,461,724 (13.57%) 85,412 (15.33%) 2306 (9.96%)  
  Hispanic 4,004,551 (22.07%) 82,669 (14.84%) 2435 (10.51%)  
  Asian/Pacific Islander 881,691 (4.86%) 23,992 (4.31%) 833 (3.60%)  
  Native American 124,300 (0.69%) 3261 (0.59%) 105 (0.45%)  
  Other 1,094,195 (6.03%) 31,571 (5.67%) 1236 (5.34%)  
  Total 18,145,755 (100.00%) 557,068 (100.00%) 23,161 (100.00%)  
Primary expected payer Medicare 47,207 (0.21%) 1380 (0.20%) 21 (0.07%) <.0001
  Medicaid 9,344,270 (42.28%) 223,397 (33.11%) 5174 (18.05%)  
  Private insurance 11,057,438 (50.03%) 409,725 (60.72%) 22,171 (77.36%)  
  Self-pay 1,030,075 (4.66%) 20,115 (2.98%) 392 (1.37%)  
  No charge 38,623 (0.17%) 683 (0.10%) 29 (0.10%)  
  Other 582,632 (2.64%) 19,455 (2.88%) 874 (3.05%)  
  Total 22,100,246 (100.00%) 674,755 (100.00%) 28,661 (100.00%)  
Region of hospital Northeast 3,672,279 (16.58%) 133,246 (19.71%) 6370 (22.18%) <.0001
  Midwest 4,767,208 (21.52%) 151,710 (22.44%) 7074 (24.63%)  
  South 8,412,784 (37.98%) 243,999 (36.10%) 9614 (33.48%)  
  West 5,296,168 (23.91%) 147,014 (21.75%) 5657 (19.70%)  
  Total 22,148,440 (100.00%) 675,969 (100.00%) 28,716 (100.00%)  
Hospital type Rural 2,697,153 (12.28%) 50,055 (7.48%) 467 (1.66%) <.0001
  Urban nonteaching 8,756,542 (39.88%) 231,462 (34.61%) 6694 (23.80%)  
  Urban teaching 10,502,357 (47.83%) 387,322 (57.91%) 20,962 (74.54%)  
  Total 21,956,052 (100.00%) 668,839 (100.00%) 28,123 (100.00%)  
Bed size of hospital Small 2,524,672 (11.50%) 59,158 (8.84%) 1227 (4.36%) <.0001
  Medium 5,918,612 (26.96%) 165,112 (24.69%) 5131 (18.24%)  
  Large 13,512,768 (61.54%) 444,569 (66.47%) 21,765 (77.39%)  
  Total 21,956,052 (100.00%) 668,839 (100.00%) 28,123 (100.00%)  
Delivery type NSVD 15,728,662 (71.01%) 192,045 (28.41%) 1686 (5.87%) <.0001
  CS 6,419,778 (28.99%) 483,924 (71.59%) 27,030 (94.13%)  
  Total 22,148,440 (100.00%) 675,969 (100.00%) 28,716 (100.00%)