2Odibo AO,Elkousy M,Ural SH,et al.Prevention of preterm birth by cerclage compared with expectant management:a systematic review[J].Obstet Gynecol Surv,2003,58(2):131-135.
3曹泽毅.中华妇产科学[M](第2版)[M].北京:人民卫生出版社,2000.2333.
二级参考文献5
1Zorzoli A, Soliani A, Perra M, et al. Cervical changes throughout pregnancy as assessed by transvaginal sonography.Obstet Gynecol, 1994,84:960- 963.
2Iams JD, Goldenberg RL, Meis PJ, et al.The Length of the cervix and the risk of spontaneous premature delivery.N Engl J Med, 1996, 334:567 - 571.
3Gudrun ER, Mellon C, Vintzileos AM, et al. Longitudinal assessment of endoeervieal length between 15 and 24 weeks,gestation in women at risk for pregnancy loss or preterm birth. Obste Gynecol, 1998,92:31 -35.
4Callen PW. Ultrasonography in Obstetrics and Gynecology.4^th edition. Philadephia WB Sauders company,2000.577 - 598.
