Table 2 The Unmatched Factors between the Male and the Female Co-twins in Mixed Gender Twins.

From: Gender Differences in Infant Mortality and Neonatal Morbidity in Mixed-Gender Twins

  The male twins The female co-twins P
Birth weight (g, Mean, SD) 2200 (796) 2094 (778) <0.001
Birth order    0.02
 First 48,650 (45.0) 48,013 (44.5)  
 Second 48,013 (44.5) 48,650 (45.0)  
 Unknown 11,375 (10.5) 11,375 (10.5)  
Methods of delivery    0.88
 C-section 71,046 (65.8) 70,883 (65.6)  
 Vaginal 29,913 (27.7) 30,076 (27.8)  
 Unknown 7079 (6.6) 7079 (6.6)