9Hack M,Fanaroff A A.Outcomes of extremely immature infants:A perinatal dilemma[J].New Eng J Med,1993,329(22):1649-1650.
10Lefebvre R,Glorieux L P S,St Larent-Gagnon T.Neonatal survival and disability rate at age 18 months for infants born between 23 and 28 weeks of gestation[J].American J Obste Gyn,1996,174(3):833-838.