Psychological follow-up study of twins from birth to five years.
D000367:Age Factors; D001724:Birth Weight; D002657:Child Development / Q000502:physiology; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007360:Intelligence; D007804:Language Development; D008297:Male; D009048:Motor Skills; D010298:Parity; D011247:Pregnancy; D012737:Sex Factors; D012801:Sibling Relations; D012959:Socioeconomic Factors; D014427:Twins