title: Natal influences and twin differences.
mesh_terms: D001034:Apgar Score; D001722:Birth Order; D001724:Birth Weight; D002675:Child, Preschool; D036861:Delivery, Obstetric; D005260:Female; D014644:Genetic Variation; D005824:Genetics, Behavioral; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007360:Intelligence; D007361:Intelligence Tests; D007743:Labor, Obstetric; D008297:Male; D008423:Maternal Age; D010641:Phenotype; D011247:Pregnancy; D011248:Pregnancy Complications; D012107:Research Design; D012189:Retrospective Studies; D014427:Twins