UpToDate
Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate®

双胎妊娠：临产与分娩

Authors
Stephen T Chasen, MD
Frank A Chervenak, MD
Section Editor
Charles J Lockwood, MD, MHCM
Deputy Editor
Vanessa A Barss, MD, FACOG
Translators
戴毅敏, 副主任医师

引言

双胎妊娠发生产时并发症(如，胎心率异常和胎先露异常相关的并发症)的风险增加。本专题将总结与双胎分娩相关的问题，如分娩的时机和方式、胎儿监护、产妇镇痛/麻醉以及分娩的处理。这些妊娠的产前评估和新生儿处理，以及单羊膜囊双胎妊娠将单独讨论。 (参见“双胎妊娠的产前问题”和“单羊膜囊双胎妊娠”和“多胞胎的新生儿期并发症、结局及管理”)

时机

自发性或医学指征性早产使得超过50%的双胎妊娠变得复杂，因此大多数情况下，分娩时机的安排不由产科医生决定[1]。然而，如果未发生自发性和医学指征性早产，双胎妊娠究竟应该何时进行分娩呢？

一般来讲，我们同意关于双胎妊娠分娩时机的专家共识指南。由尤尼斯·肯尼迪·施莱佛美国国家儿童健康与人类发育研究所(National Institute of Child Health and Human Development, NICHD)和母胎医学协会(Society for Maternal-Fetal Medicine, SMFM)举办的研讨会达成的一致意见建议，无并发症的双绒毛膜双胎在38周时分娩，无并发症的单绒毛膜双羊膜囊双胎在34-37周时分娩[2]。英国国家卫生与临床优化研究所(National Institute for Health and Clinical Excellence, NICE)推荐，从妊娠37周起双绒毛膜双胎可进行择期分娩，而从妊娠36周起单绒毛膜双胎可进行择期分娩(完成一个疗程的皮质类固醇后)[3]。美国妇产科医师学会(American College of Obstetricians and Gynecologists, ACOG)推荐，无并发症的双绒毛膜双胎的分娩时机是妊娠38周至38+6周，无并发症的单绒毛膜双胎为妊娠34周-37+6周[4,5]。伴有胎儿宫内生长受限的双胎妊娠则应提前分娩，提前的时机取决于临床情况。

双绒毛膜/双羊膜囊双胎妊娠 — 对于无并发症的正常双绒毛膜/双羊膜囊双胎妊娠，我们建议在妊娠38-40周之间择期分娩。

关于双绒毛膜/双羊膜囊双胎妊娠的最佳分娩时机，目前还没有高质量的随机试验数据，可以让我们以此为根据作出合适的推荐。根据我们的经验和下文所列的数据，我们和其他医生都认为双绒毛膜/双羊膜囊双胎妊娠应避免在妊娠38周前择期分娩(即，在没有出现常规母胎分娩指征的情况下)[5-8]。如果要考虑在38周前进行择期分娩，应评估胎肺成熟度[9]。

                            

Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: 2017-06 . | This topic last updated: 2017-01-08.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
References
Top
  1. Kogan MD, Alexander GR, Kotelchuck M, et al. Trends in twin birth outcomes and prenatal care utilization in the United States, 1981-1997. JAMA 2000; 284:335.
  2. Spong CY, Mercer BM, D'alton M, et al. Timing of indicated late-preterm and early-term birth. Obstet Gynecol 2011; 118:323.
  3. Multiple pregnancy: The management of twin and triplet pregnancies in the antenatal period http://publications.nice.org.uk/multiple-pregnancy-cg129 (Accessed on April 10, 2012).
  4. American College of Obstetricians and Gynecologists. ACOG committee opinion no. 560: Medically indicated late-preterm and early-term deliveries. Obstet Gynecol 2013; 121:908.
  5. American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine. ACOG Practice Bulletin No. 144: Multifetal gestations: twin, triplet, and higher-order multifetal pregnancies. Obstet Gynecol 2014; 123:1118.
  6. Chasen ST, Madden A, Chervenak FA. Cesarean delivery of twins and neonatal respiratory disorders. Am J Obstet Gynecol 1999; 181:1052.
  7. Cruikshank DP. Intrapartum management of twin gestations. Obstet Gynecol 2007; 109:1167.
  8. Breathnach FM, McAuliffe FM, Geary M, et al. Optimum timing for planned delivery of uncomplicated monochorionic and dichorionic twin pregnancies. Obstet Gynecol 2012; 119:50.
  9. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 97: Fetal lung maturity. Obstet Gynecol 2008; 112:717.
  10. Luke B. Reducing fetal deaths in multiple births: optimal birthweights and gestational ages for infants of twin and triplet births. Acta Genet Med Gemellol (Roma) 1996; 45:333.
  11. Minakami H, Sato I. Reestimating date of delivery in multifetal pregnancies. JAMA 1996; 275:1432.
  12. Sairam S, Costeloe K, Thilaganathan B. Prospective risk of stillbirth in multiple-gestation pregnancies: a population-based analysis. Obstet Gynecol 2002; 100:638.
  13. Kahn B, Lumey LH, Zybert PA, et al. Prospective risk of fetal death in singleton, twin, and triplet gestations: implications for practice. Obstet Gynecol 2003; 102:685.
  14. Suzuki S, Otsubo Y, Sawa R, et al. Clinical trial of induction of labor versus expectant management in twin pregnancy. Gynecol Obstet Invest 2000; 49:24.
  15. Dodd JM, Crowther CA, Haslam RR, et al. Elective birth at 37 weeks of gestation versus standard care for women with an uncomplicated twin pregnancy at term: the Twins Timing of Birth Randomised Trial. BJOG 2012; 119:964.
  16. Dodd JM, Deussen AR, Grivell RM, Crowther CA. Elective birth at 37 weeks' gestation for women with an uncomplicated twin pregnancy. Cochrane Database Syst Rev 2014; :CD003582.
  17. Luke B, Minogue J, Witter FR, et al. The ideal twin pregnancy: patterns of weight gain, discordancy, and length of gestation. Am J Obstet Gynecol 1993; 169:588.
  18. Cincotta, RB, Flenady, V, Hockey, R, King, J. When should twins be delivered? Gestational age-specific stillbirth risk of twins vs singletons. Perinatal Society of Australia and New Zealand, 5th annual congress, 2001 March 13-16, Canberra, Australia 2001:22.
  19. Cheung YB, Yip P, Karlberg J. Mortality of twins and singletons by gestational age: a varying-coefficient approach. Am J Epidemiol 2000; 152:1107.
  20. Hartley RS, Emanuel I, Hitti J. Perinatal mortality and neonatal morbidity rates among twin pairs at different gestational ages: optimal delivery timing at 37 to 38 weeks' gestation. Am J Obstet Gynecol 2001; 184:451.
  21. Dodd, JM, Robinson, JS, Crowther, CA, et al. Stillbirth and neonatal outcomes in twin and singleton pregnancies in South Australia, 1991-2000. Perinatal Society of Australia and New Zealand 6th Annual Congress; 2002 March 9-13. Australia, 2002.
  22. Luke B, Brown MB, Alexandre PK, et al. The cost of twin pregnancy: maternal and neonatal factors. Am J Obstet Gynecol 2005; 192:909.
  23. Cheung, YB, Yip, P, Karlberg, J. Mortality of twins and singletons by gestational age: a varying coefficient approach. Am J Epidemiol 2000; 152:1117.
  24. Dodd JM, Robinson JS, Crowther CA, Chan A. Stillbirth and neonatal outcomes in South Australia, 1991-2000. Am J Obstet Gynecol 2003; 189:1731.
  25. Bakr AF, Karkour T. What is the optimal gestational age for twin delivery. BMC Pregnancy Childbirth 2006; 6:3.
  26. Udom-Rice I, Inglis SR, Skupski D, et al. Optimal gestational age for twin delivery. J Perinatol 2000; 20:231.
  27. Soucie JE, Yang Q, Wen SW, et al. Neonatal mortality and morbidity rates in term twins with advancing gestational age. Am J Obstet Gynecol 2006; 195:172.
  28. Wood S, Tang S, Ross S, Sauve R. Stillbirth in twins, exploring the optimal gestational age for delivery: a retrospective cohort study. BJOG 2014; 121:1284.
  29. Leveno KJ, Quirk JG, Whalley PJ, et al. Fetal lung maturation in twin gestation. Am J Obstet Gynecol 1984; 148:405.
  30. Winn HN, Romero R, Roberts A, et al. Comparison of fetal lung maturation in preterm singleton and twin pregnancies. Am J Perinatol 1992; 9:326.
  31. Friedman SA, Schiff E, Kao L, et al. Do twins mature earlier than singletons? Results from a matched cohort study. Am J Obstet Gynecol 1997; 176:1193.
  32. Marttila R, Kaprio J, Hallman M. Respiratory distress syndrome in twin infants compared with singletons. Am J Obstet Gynecol 2004; 191:271.
  33. Morrison JJ, Rennie JM, Milton PJ. Neonatal respiratory morbidity and mode of delivery at term: influence of timing of elective caesarean section. Br J Obstet Gynaecol 1995; 102:101.
  34. Blickstein I. Cesarean section for all twins? J Perinat Med 2000; 28:169.
  35. Lewis DF, Fontenot MT, Robichaux AG, et al. Respiratory morbidity in well-dated twins approaching term. What are the risks of elective delivery? J Reprod Med 2002; 47:841.
  36. Mackenzie MW. Predicting concordance of biochemical lung maturity in the preterm twin gestation. J Matern Fetal Neonatal Med 2002; 12:50.
  37. Whitworth NS, Magann EF, Morrison JC. Evaluation of fetal lung maturity in diamniotic twins. Am J Obstet Gynecol 1999; 180:1438.
  38. Cleary-Goldman J, D'Alton ME. Uncomplicated monochorionic diamniotic twins and the timing of delivery. PLoS Med 2005; 2:e180.
  39. Simões T, Amaral N, Lerman R, et al. Prospective risk of intrauterine death of monochorionic-diamniotic twins. Am J Obstet Gynecol 2006; 195:134.
  40. Barigye O, Pasquini L, Galea P, et al. High risk of unexpected late fetal death in monochorionic twins despite intensive ultrasound surveillance: a cohort study. PLoS Med 2005; 2:e172.
  41. Hack KE, Derks JB, Elias SG, et al. Increased perinatal mortality and morbidity in monochorionic versus dichorionic twin pregnancies: clinical implications of a large Dutch cohort study. BJOG 2008; 115:58.
  42. Sullivan AE, Hopkins PN, Weng HY, et al. Delivery of monochorionic twins in the absence of complications: analysis of neonatal outcomes and costs. Am J Obstet Gynecol 2012; 206:257.e1.
  43. Hack KE, Derks JB, Elias SG, et al. Perinatal mortality and mode of delivery in monochorionic diamniotic twin pregnancies ≥ 32 weeks of gestation: a multicentre retrospective cohort study. BJOG 2011; 118:1090.
  44. Robinson BK, Miller RS, D'Alton ME, Grobman WA. Effectiveness of timing strategies for delivery of monochorionic diamniotic twins. Am J Obstet Gynecol 2012; 207:53.e1.
  45. Beasley E, Megerian G, Gerson A, Roberts NS. Monoamniotic twins: case series and proposal for antenatal management. Obstet Gynecol 1999; 93:130.
  46. Rodis JF, McIlveen PF, Egan JF, et al. Monoamniotic twins: improved perinatal survival with accurate prenatal diagnosis and antenatal fetal surveillance. Am J Obstet Gynecol 1997; 177:1046.
  47. American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine. Obstetric care consensus no. 1: safe prevention of the primary cesarean delivery. Obstet Gynecol 2014; 123:693.
  48. Steer P. Perinatal death in twins. BMJ 2007; 334:545.
  49. Smith GC, Shah I, White IR, et al. Mode of delivery and the risk of delivery-related perinatal death among twins at term: a retrospective cohort study of 8073 births. BJOG 2005; 112:1139.
  50. Smith GC, Fleming KM, White IR. Birth order of twins and risk of perinatal death related to delivery in England, Northern Ireland, and Wales, 1994-2003: retrospective cohort study. BMJ 2007; 334:576.
  51. Meyer MC. Translating data to dialogue: how to discuss mode of delivery with your patient with twins. Am J Obstet Gynecol 2006; 195:899.
  52. Hogle KL, Hutton EK, McBrien KA, et al. Cesarean delivery for twins: a systematic review and meta-analysis. Am J Obstet Gynecol 2003; 188:220.
  53. Rossi AC, Mullin PM, Chmait RH. Neonatal outcomes of twins according to birth order, presentation and mode of delivery: a systematic review and meta-analysis. BJOG 2011; 118:523.
  54. Vendittelli F, Rivière O, Crenn-Hébert C, et al. Is a planned cesarean necessary in twin pregnancies? Acta Obstet Gynecol Scand 2011; 90:1147.
  55. Hofmeyr GJ, Barrett JF, Crowther CA. Planned caesarean section for women with a twin pregnancy. Cochrane Database Syst Rev 2011; :CD006553.
  56. Sibony O, Touitou S, Luton D, et al. A comparison of the neonatal morbidity of second twins to that of a low-risk population. Eur J Obstet Gynecol Reprod Biol 2003; 108:157.
  57. Barrett JF, Hannah ME, Hutton EK, et al. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. N Engl J Med 2013; 369:1295.
  58. Zhang J, Bowes WA Jr, Grey TW, McMahon MJ. Twin delivery and neonatal and infant mortality: a population-based study. Obstet Gynecol 1996; 88:593.
  59. Barrett JM, Staggs SM, Van Hooydonk JE, et al. The effect of type of delivery upon neonatal outcome in premature twins. Am J Obstet Gynecol 1982; 143:360.
  60. Alfirevic Z, Milan SJ, Livio S. Caesarean section versus vaginal delivery for preterm birth in singletons. Cochrane Database Syst Rev 2013; :CD000078.
  61. Chasen ST, Spiro SJ, Kalish RB, Chervenak FA. Changes in fetal presentation in twin pregnancies. J Matern Fetal Neonatal Med 2005; 17:45.
  62. Dodd JM, Crowther CA. Evidence-based care of women with a multiple pregnancy. Best Pract Res Clin Obstet Gynaecol 2005; 19:131.
  63. Blickstein I, Goldman RD, Kupferminc M. Delivery of breech first twins: a multicenter retrospective study. Obstet Gynecol 2000; 95:37.
  64. Arabin B, Kyvernitakis I. Vaginal delivery of the second nonvertex twin: avoiding a poor outcome when the presenting part is not engaged. Obstet Gynecol 2011; 118:950.
  65. Rabinovici J, Barkai G, Reichman B, et al. Randomized management of the second nonvertex twin: vaginal delivery or cesarean section. Am J Obstet Gynecol 1987; 156:52.
  66. Chervenak FA, Johnson RE, Berkowitz RL, Hobbins JC. Intrapartum external version of the second twin. Obstet Gynecol 1983; 62:160.
  67. Chervenak FA, Johnson RE, Youcha S, et al. Intrapartum management of twin gestation. Obstet Gynecol 1985; 65:119.
  68. Mauldin JG, Newman RB, Mauldin PD. Cost-effective delivery management of the vertex and nonvertex twin gestation. Am J Obstet Gynecol 1998; 179:864.
  69. Chauhan SP, Roberts WE, McLaren RA, et al. Delivery of the nonvertex second twin: breech extraction versus external cephalic version. Am J Obstet Gynecol 1995; 173:1015.
  70. Davison L, Easterling TR, Jackson JC, Benedetti TJ. Breech extraction of low-birth-weight second twins: can cesarean section be justified? Am J Obstet Gynecol 1992; 166:497.
  71. Morales WJ, O'Brien WF, Knuppel RA, et al. The effect of mode of delivery on the risk of intraventricular hemorrhage in nondiscordant twin gestations under 1500 g. Obstet Gynecol 1989; 73:107.
  72. Winn HN, Cimino J, Powers J, et al. Intrapartum management of nonvertex second-born twins: a critical analysis. Am J Obstet Gynecol 2001; 185:1204.
  73. Acker D, Lieberman M, Holbrook RH, et al. Delivery of the second twin. Obstet Gynecol 1982; 59:710.
  74. Blickstein I, Schwartz-Shoham Z, Lancet M, Borenstein R. Vaginal delivery of the second twin in breech presentation. Obstet Gynecol 1987; 69:774.
  75. Rabinovici J, Barkai G, Reichman B, et al. Internal podalic version with unruptured membranes for the second twin in transverse lie. Obstet Gynecol 1988; 71:428.
  76. Gocke SE, Nageotte MP, Garite T, et al. Management of the nonvertex second twin: primary cesarean section, external version, or primary breech extraction. Am J Obstet Gynecol 1989; 161:111.
  77. Adam C, Allen AC, Baskett TF. Twin delivery: influence of the presentation and method of delivery on the second twin. Am J Obstet Gynecol 1991; 165:23.
  78. Fishman A, Grubb DK, Kovacs BW. Vaginal delivery of the nonvertex second twin. Am J Obstet Gynecol 1993; 168:861.
  79. Kaplan B, Peled Y, Rabinerson D, et al. Successful external version of B-twin after the birth of A-twin for vertex--non-vertex twins. Eur J Obstet Gynecol Reprod Biol 1995; 58:157.
  80. Wells SR, Thorp JM Jr, Bowes WA Jr. Management of the nonvertex second twin. Surg Gynecol Obstet 1991; 172:383.
  81. Peaceman AM, Kuo L, Feinglass J. Infant morbidity and mortality associated with vaginal delivery in twin gestations. Am J Obstet Gynecol 2009; 200:462.e1.
  82. Fox NS, Silverstein M, Bender S, et al. Active second-stage management in twin pregnancies undergoing planned vaginal delivery in a U.S. population. Obstet Gynecol 2010; 115:229.
  83. Yang Q, Wen SW, Chen Y, et al. Neonatal death and morbidity in vertex-nonvertex second twins according to mode of delivery and birth weight. Am J Obstet Gynecol 2005; 192:840.
  84. Ford AA, Bateman BT, Simpson LL. Vaginal birth after cesarean delivery in twin gestations: a large, nationwide sample of deliveries. Am J Obstet Gynecol 2006; 195:1138.
  85. Miller DA, Mullin P, Hou D, Paul RH. Vaginal birth after cesarean section in twin gestation. Am J Obstet Gynecol 1996; 175:194.
  86. Sansregret A, Bujold E, Gauthier RJ. Twin delivery after a previous caesarean: a twelve-year experience. J Obstet Gynaecol Can 2003; 25:294.
  87. Delaney T, Young DC. Trial of labour compared to elective Caesarean in twin gestations with a previous Caesarean delivery. J Obstet Gynaecol Can 2003; 25:289.
  88. Myles T. Vaginal birth of twins after a previous Cesarean section. J Matern Fetal Med 2001; 10:171.
  89. Odeh M, Tarazova L, Wolfson M, Oettinger M. Evidence that women with a history of cesarean section can deliver twins safely. Acta Obstet Gynecol Scand 1997; 76:663.
  90. Strong TH Jr, Phelan JP, Ahn MO, Sarno AP Jr. Vaginal birth after cesarean delivery in the twin gestation. Am J Obstet Gynecol 1989; 161:29.
  91. Cahill A, Stamilio DM, Paré E, et al. Vaginal birth after cesarean (VBAC) attempt in twin pregnancies: is it safe? Am J Obstet Gynecol 2005; 193:1050.
  92. Silver RK, Haney EI, Grobman WA, et al. Comparison of active phase labor between triplet, twin, and singleton gestations. J Soc Gynecol Investig 2000; 7:297.
  93. Schiff E, Cohen SB, Dulitzky M, et al. Progression of labor in twin versus singleton gestations. Am J Obstet Gynecol 1998; 179:1181.
  94. Leftwich HK, Zaki MN, Wilkins I, Hibbard JU. Labor patterns in twin gestations. Am J Obstet Gynecol 2013; 209:254.e1.
  95. Fausett MB, Barth WH Jr, Yoder BA, Satin AJ. Oxytocin labor stimulation of twin gestations: effective and efficient. Obstet Gynecol 1997; 90:202.
  96. Neimand KM, Gibstein A, Rosenthal AH. Oxytocin in twin gestation. Am J Obstet Gynecol 1967; 99:533.
  97. Fleming AD, Rayburn WF, Mandsager NT, et al. Perinatal outcomes of twin pregnancies at term. J Reprod Med 1990; 35:881.
  98. Leroy F. Oxytocin treatment in twin pregnancy labour. Acta Genet Med Gemellol (Roma) 1979; 28:303.
  99. Dias T, Ladd S, Mahsud-Dornan S, et al. Systematic labeling of twin pregnancies on ultrasound. Ultrasound Obstet Gynecol 2011; 38:130.
  100. Bronshtein M, Bar-Hava I, Ben-Rafael Z, et al. Twin gestation: is there a correlation between the location of the gestational sacs at the beginning of pregnancy, and the order of delivery. Eur J Obstet Gynecol Reprod Biol 1998; 77:189.
  101. Chasen ST, Al-Kouatly HB, Chervenak FA. Correlation between prenatal and neonatal birth order in twin pregnancy. Am J Perinatol 2001; 18:151.
  102. D'Antonio F, Dias T, B. Thilaganathan on behalf of the Southwest Thames Obstetric Research Collaborative (STORK). Does antenatal ultrasound labeling predict birth order in twin pregnancies? Ultrasound Obstet Gynecol 2013; 41:274.
  103. Smith GC, Pell JP, Dobbie R. Birth order, gestational age, and risk of delivery related perinatal death in twins: retrospective cohort study. BMJ 2002; 325:1004.
  104. Sheay W, Ananth CV, Kinzler WL. Perinatal mortality in first- and second-born twins in the United States. Obstet Gynecol 2004; 103:63.
  105. Luo ZC, Ouyang F, Zhang J, Klebanoff M. Perinatal mortality in second- vs firstborn twins: a matter of birth size or birth order? Am J Obstet Gynecol 2014; 211:153.e1.
  106. Armson BA, O'Connell C, Persad V, et al. Determinants of perinatal mortality and serious neonatal morbidity in the second twin. Obstet Gynecol 2006; 108:556.
  107. Görbe E, Chasen S, Harmath A, et al. Very-low-birthweight breech infants: short-term outcome by method of delivery. J Matern Fetal Med 1997; 6:155.
  108. Dufour P, Vinatier D, Vanderstichele S, et al. Intravenous nitroglycerin for internal podalic version of the second twin in transverse lie. Obstet Gynecol 1998; 92:416.
  109. Caukwell S, Murphy DJ. The effect of mode of delivery and gestational age on neonatal outcome of the non-cephalic- presenting second twin. Am J Obstet Gynecol 2002; 187:1356.
  110. Thompson JP, Johnson CE. Survival and management of the second-born twin. Obstet Gynecol 1966; 27:827.
  111. Second twin. Br Med J 1968; 2:641.
  112. LITTLE WA, FRIEDMAN EA. The twin delivery: factors influencing second twin mortality. Obstet Gynecol Surv 1958; 13:611.
  113. Rayburn WF, Lavin JP Jr, Miodovnik M, Varner MW. Multiple gestation: time interval between delivery of the first and second twins. Obstet Gynecol 1984; 63:502.
  114. Rydhström H, Ingemarsson I. Interval between birth of the first and the second twin and its impact on second twin perinatal mortality. J Perinat Med 1990; 18:449.
  115. Brown HL, Miller JM Jr, Neumann DE, et al. Umbilical cord blood gas assessment of twins. Obstet Gynecol 1990; 75:826.
  116. Wen SW, Fung KF, Oppenheimer L, et al. Occurrence and predictors of cesarean delivery for the second twin after vaginal delivery of the first twin. Obstet Gynecol 2004; 103:413.
  117. Breathnach FM, McAuliffe FM, Geary M, et al. Prediction of safe and successful vaginal twin birth. Am J Obstet Gynecol 2011; 205:237.e1.
  118. Engelbrechtsen L, Nielsen EH, Perin T, et al. Cesarean section for the second twin: a population-based study of occurrence and outcome. Birth 2013; 40:10.
  119. Yang Q, Wen SW, Chen Y, et al. Occurrence and clinical predictors of operative delivery for the vertex second twin after normal vaginal delivery of the first twin. Am J Obstet Gynecol 2005; 192:178.
  120. Cameron AH. The Birmingham twin survey. Proc R Soc Med 1968; 61:229.
  121. Blickstein I, Jones C, Keith LG. Zygotic-splitting rates after single-embryo transfers in in vitro fertilization. N Engl J Med 2003; 348:2366.
  122. Souter VL, Kapur RP, Nyholt DR, et al. A report of dizygous monochorionic twins. N Engl J Med 2003; 349:154.
  123. Yoon G, Beischel LS, Johnson JP, Jones MC. Dizygotic twin pregnancy conceived with assisted reproductive technology associated with chromosomal anomaly, imprinting disorder, and monochorionic placentation. J Pediatr 2005; 146:565.
  124. Miura K, Niikawa N. Do monochorionic dizygotic twins increase after pregnancy by assisted reproductive technology? J Hum Genet 2005; 50:1.
  125. Yanaihara A, Yorimitsu T, Motoyama H, et al. Monozygotic multiple gestation following in vitro fertilization: analysis of seven cases from Japan. J Exp Clin Assist Reprod 2007; 4:4.
  126. Hackmon R, Jormark S, Cheng V, et al. Monochorionic dizygotic twins in a spontaneous pregnancy: a rare case report. J Matern Fetal Neonatal Med 2009; 22:708.
  127. Smeets D, van Vugt JM, Gomes I, et al. Monochorionic dizygous twins presenting with blood chimerism and discordant sex. Twin Res Hum Genet 2013; 16:799.
  128. Derom R, Bryan E, Derom C, et al. Twins, chorionicity and zygosity. Twin Res 2001; 4:134.
  129. Lewi L, Deprest J, Hecher K. The vascular anastomoses in monochorionic twin pregnancies and their clinical consequences. Am J Obstet Gynecol 2013; 208:19.
  130. Denbow ML, Cox P, Taylor M, et al. Placental angioarchitecture in monochorionic twin pregnancies: relationship to fetal growth, fetofetal transfusion syndrome, and pregnancy outcome. Am J Obstet Gynecol 2000; 182:417.
  131. Lewi L, Cannie M, Blickstein I, et al. Placental sharing, birthweight discordance, and vascular anastomoses in monochorionic diamniotic twin placentas. Am J Obstet Gynecol 2007; 197:587.e1.