Placental type and Bayley Mental Development scores in 18-month-old twins.
D000367:Age Factors; D001724:Birth Weight; D002657:Child Development; D002823:Chorion / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007223:Infant; D007360:Intelligence; D007361:Intelligence Tests; D011247:Pregnancy; D012923:Social Class; D014427:Twins; D014430:Twins, Monozygotic