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Vol. 95, No. 1, 2009
Issue release date: December 2008
Free Access
Neonatology 2009;95:6–14
(DOI:10.1159/000151750)

Outcomes of Multiplets

Shinwell E.S.a · Haklai T.b · Eventov-Friedman S.a
aDepartment of Neonatology, Kaplan Medical Center, Rehovot, and Hebrew University, and bDepartment of Health Information, Ministry of Health, Jerusalem, Israel
email Corresponding Author

Abstract

Outcomes, both short and long term, differ between singletons and multiplets. Recently, a number of large, well-designed studies have clarified these differences, particularly in light of major changes in perinatal and neonatal care that have influenced changing outcomes. Accordingly, this article will review risks for singletons, twins and higher-order multiples as whole groups and also after correction for gestational age and other potential confounding variables that differ markedly between the groups. In addition, we will focus on the effects of certain factors such as antenatal steroid therapy and gender. Finally, we will detail the specific long-term risks for multiples in terms of growth and neurodevelopmental disabilities.


 goto top of outline Key Words

  • Twins
  • Triplets
  • Multiple pregnancy
  • Neonatal outcome
  • Cerebral palsy

 goto top of outline Abstract

Outcomes, both short and long term, differ between singletons and multiplets. Recently, a number of large, well-designed studies have clarified these differences, particularly in light of major changes in perinatal and neonatal care that have influenced changing outcomes. Accordingly, this article will review risks for singletons, twins and higher-order multiples as whole groups and also after correction for gestational age and other potential confounding variables that differ markedly between the groups. In addition, we will focus on the effects of certain factors such as antenatal steroid therapy and gender. Finally, we will detail the specific long-term risks for multiples in terms of growth and neurodevelopmental disabilities.

Copyright © 2008 S. Karger AG, Basel


 goto top of outline References
  1. Martin JA, Kung HC, Mathews TJ, Hoyert DL, Strobino DM, Guyer B, Sutton SR: Annual summary of vital statistics: 2006. Pediatrics 2008;121:788–801.
  2. Haklai T: Personal Communication. Department of Health Information, Ministry of Health, Israel, 2008.
  3. Fanaroff AA, Stoll BJ, Wright LL, Carlo WA, Ehrenkranz RA, Stark AR, Bauer CR, Donovan EF, Korones SB, Laptook AR, Lemons JA, Oh W, Papile LA, Shankaran S, Stevenson DK, Tyson JE, Poole WK: Trends in neonatal morbidity and mortality for very low birthweight infants. Am J Obstet Gynecol 2007;196:147.e1–147.e8.
  4. Report of the Expert Group on Multiple Births after IVF: One child at a time. Reducing multiple births after IVF. London, Human Fertilisation and Embryology Authority, 2006.
  5. Reichman B: Personal Communication. Israel VLBW Neonatal Database, 2007.
  6. Cheang CU, Huang LS, Lee TH, Liu CH, Shih YT, Lee MS: A comparison of the outcomes between twin and reduced twin pregnancies produced through assisted reproduction. Fertil Steril 2007;88:47–52.
  7. Martin JA, Park MM: Trends in twin and triplet births: 1980–1997. Natl Vital Stat Rep 1999;47:1–16.
  8. Luke B, Keith LG: The contribution of singletons, twins and triplets to low birth weight, infant mortality and handicap in the United States. J Reprod Med 1992;37:661–666.
  9. Imaizumi Y: Perinatal mortality in triplet births in Japan: time trends and factors influencing mortality. Twin Res 2003;6:1–6.
  10. Misra DP, Ananth CV: Infant mortality among singletons and twins in the United States during two decades: effects of maternal age. Pediatrics 2002;110:1163–1168.
  11. Alexander GR, Kogan M, Martin J, Papiernik E: What are the fetal growth patterns of singletons, twins, and triplets in the United States? Clin Obstet Gynecol 1998;41:114–125.
  12. Ballabh P, Kumari J, Al-Kouatly HB, Yih M, Arevalo R, Rosenwaks Z, Krauss AN: Neonatal outcome of triplet versus twin and singleton pregnancies: a matched case control study. Eur J Obstet Gynecol Reprod Biol 2003;107:28–36.
  13. Suri K, Bhandari V, Lerer T, Rosenkrantz TS, Hussain N: Morbidity and mortality of preterm twins and higher-order multiple births. J Perinatol 2001;21:293–299.
  14. Nielsen HC, Harvey-Wilkes K, MacKinnon B, Hung S: Neonatal outcome of very premature infants from multiple and singleton gestations. Am J Obstet Gynecol 1997;177:653–659.
  15. Maayan-Metzger A, Naor N, Sirota L: Comparative outcome study between triplet and singleton preterm newborns. Acta Paediatr 2002;91:1208–1211.
  16. Synnes AR, Ling EW, Whitfield MF, Mackinnon M, Lopes L, Wong G, Effer SB: Perinatal outcomes of a large cohort of extremely low gestational age infants (23–28 completed weeks of gestation). J Pediatr 1994;125:952–960.
  17. Buekens P, Wilcox A: Why do small twins have a lower mortality rate than small singletons? Am J Obstet Gynecol 1993;168:937–941.
  18. Ericson A, Gunnarskog J, Kallen B, Olausson PO: A registry study of very low birthweight liveborn infants in Sweden, 1973–1988. Acta Obstet Gynecol Scand 1992;71:104–111.
  19. Donovan EF, Ehrenkranz RA, Shankaran S, Stevenson DK, Wright LL, Younes N, Fanaroff AA, Korones SB, Stoll BJ, Tyson JE, Bauer CR, Lemons JA, Oh W, Papile LA: Outcomes of very low birth weight twins cared for in the National Institute of Child Health and Human Development Neonatal Research Network’s intensive care units. Am J Obstet Gynecol 1998;179:742–749.
  20. Shinwell ES, Blickstein I, Lusky A, Reichman B: Excess risk of mortality in very low birthweight triplets: a national, population-based study. Arch Dis Child Fetal Neonatal Ed 2003;88:F36–F40.
  21. Garite TJ, Clark RH, Elliott JP, Thorp JA: Twins and triplets: the effect of plurality and growth on neonatal outcome compared with singleton infants. Am J Obstet Gynecol 2004;191:700–707.
  22. Qiu X, Lee SK, Tan K, Piedboeuf B, Canning R: Comparison of singleton and multiple-birth outcomes of infants born at or before 32 weeks of gestation. Obstet Gynecol 2008;111:365–371.
  23. Friling R, Axer-Siegel R, Hersocovici Z, Weinberger D, Sirota L, Snir M: Retinopathy of prematurity in assisted versus natural conception and singleton versus multiple births. Ophthalmology 2007;114:321–324.
  24. Tyson JE, Parikh NA, Langer J, Green C, Higgins RD: Intensive care for extreme prematurity-moving beyond gestational age. N Engl J Med 2008;358:1672–1681.
  25. Blickstein I, Shinwell ES, Lusky A, Reichman B: Plurality-dependent risk of respiratory distress syndrome among very-low-birth-weight infants and antepartum corticosteroid treatment. Am J Obstet Gynecol 2005;192:360–364.
  26. Blickstein I, Reichman B, Lusky A, Shinwell ES: Plurality-dependent risk of severe intraventricular hemorrhage among very low birth weight infants and antepartum corticosteroid treatment. Am J Obstet Gynecol 2006;194:1329–1333.
  27. Shinwell ES, Reichman B, Lerner-Geva L, Boyko V, Blickstein I: ‘Masculinizing’ effect on respiratory morbidity in girls from unlike-sex preterm twins: a possible transchorionic paracrine effect. Pediatrics 2007;120:e447–e453.
  28. The ESHRE Capri Workshop Group: Multiple gestation pregnancy. Hum Reprod 2000;15:1856–1864.
  29. Blickstein I: Growth aberration in multiple pregnancy. Obstet Gynecol Clin North Am 2005;32:39–54.
  30. Buckler JM, Green M: Birth weight and head circumference standards for English twins. Arch Dis Child 1994;71:516–521.
  31. Ooki S, Yokoyama Y: Reference birth weight, length, chest circumference, and head circumference by gestational age in Japanese twins. J Epidemiol 2003;13:333–341.
  32. Dollberg G, Dollberg S: Fetal growth curves. Isr Med Assoc J 2006;8:518.
  33. Ooki S, Yokoyama Y: Physical growth charts from birth to six years of age in Japanese twins. J Epidemiol 2004;14:151–160.
  34. Estourgie-van Burk GF, Bartels M, van Beijsterveldt TC, Delemarre-van de Waal HA, Boomsma DI: Body size in five-year-old twins: heritability and comparison to singleton standards. Twin Res Hum Genet 2006;9:646–655.
  35. Buckler JM, Green M: The growth of twins between the ages of 2 and 9 years. Ann Hum Biol 2008;35:75–92.
  36. Karlberg J, Luo ZC: Foetal size to final height. Acta Paediatr 2000;89:632–636.
  37. Luke B, Leurgans S, Keith L, Keith D: The childhood growth of twin children. Acta Genet Med Gemellol (Roma) 1995;44:169–178.
  38. Keet MP, Jaroszewicz AM, Lombard CJ: Follow-up study of physical growth of monozygous twins with discordant within-pair birth weights. Pediatrics 1986;77:336–344.
  39. Monset-Couchard M, de Bethmann O, Relier JP: Long-term outcome of small versus appropriate size for gestational age co-twins/triplets. Arch Dis Child Fetal Neonatal Ed 2004;89:F310–F314.
  40. Ali MA, Ashizawa K, Kato S, Kouchi M, Koyama C, Hoshi H: Biological variables in height growth of Japanese twins: a comparison with those of singletons. Ann Hum Biol 2007;34:283–295.
  41. Luke B, Brown MB, Hediger ML, Misiunas RB, Anderson E: Perinatal and early childhood outcomes of twins versus triplets. Twin Res Hum Genet 2006;9:81–88.
  42. Laplaza FJ, Root L, Tassanawipas A, Cervera P: Cerebral palsy in twins. Dev Med Child Neurol 1992;34:1053–1063.
  43. Pharoah PO, Cooke T: Cerebral palsy and multiple births. Arch Dis Child Fetal Neonatal Ed 1996;75:F174–F177.
  44. Liu J, Li Z, Lin Q, Zhao P, Zhao F, Hong S, Li S: Cerebral palsy and multiple births in China. Int J Epidemiol 2000;29:292–299.
  45. Topp M, Huusom LD, Langhoff-Roos J, Delhumeau C, Hutton JL, Dolk H: Multiple birth and cerebral palsy in Europe: a multicenter study. Acta Obstet Gynecol Scand 2004;83:548–553.
  46. Bonellie SR, Currie D, Chalmers J: Comparison of risk factors for cerebral palsy in twins and singletons. Dev Med Child Neurol 2005;47:587–591.
  47. Petterson B, Nelson KB, Watson L, Stanley F: Twins, triplets, and cerebral palsy in births in Western Australia in the 1980s. BMJ 1993;307:1239–1243.
  48. Bax M, Tydeman C, Flodmark O: Clinical and MRI correlates of cerebral palsy: the European Cerebral Palsy Study. JAMA 2006;296:1602–1608.
  49. Pharoah PO: Risk of cerebral palsy in multiple pregnancies. Clin Perinatol 2006;33:301–313.
  50. Grether JK, Nelson KB, Cummins SK: Twinning and cerebral palsy: experience in four northern California counties, births 1983 through 1985. Pediatrics 1993;92:854–858.
  51. Williams K, Hennessy E, Alberman E: Cerebral palsy: effects of twinning, birthweight, and gestational age. Arch Dis Child Fetal Neonatal Ed 1996;75:F178–F182.
  52. Scher AI, Petterson B, Blair E, Ellenberg JH, Grether JK, Haan E, Reddihough DS, Yeargin-Allsopp M, Nelson KB: The risk of mortality or cerebral palsy in twins: a collaborative population-based study. Pediatr Res 2002;52:671–681.
  53. Yokoyama Y, Shimizu T, Hayakawa K: Prevalence of cerebral palsy in twins, triplets and quadruplets. Int J Epidemiol 1995;24:943–948.
  54. Pharoah PO, Adi Y: Consequences of in-utero death in a twin pregnancy. Lancet 2000;355:1597–1602.
  55. Pharoah PO, Cooke RW: A hypothesis for the aetiology of spastic cerebral palsy – the vanishing twin. Dev Med Child Neurol 1997;39:292–296.
  56. Glinianaia SV, Pharoah PO, Wright C, Rankin JM: Fetal or infant death in twin pregnancy: neurodevelopmental consequence for the survivor. Arch Dis Child Fetal Neonatal Ed 2002;86:F9–F15.
  57. Ong SS, Zamora J, Khan KS, Kilby MD: Prognosis for the co-twin following single-twin death: a systematic review. BJOG 2006;113:992–998.
  58. Lopriore E, Nagel HT, Vandenbussche FP, Walther FJ: Long-term neurodevelopmental outcome in twin-to-twin transfusion syndrome. Am J Obstet Gynecol 2003;189:1314–1319.
  59. Dickinson JE, Duncombe GJ, Evans SF, French NP, Hagan R: The long-term neurologic outcome of children from pregnancies complicated by twin-to-twin transfusion syndrome. BJOG 2005;112:63–68.
  60. Lopriore E, Middeldorp JM, Sueters M, Oepkes D, Vandenbussche FP, Walther FJ: Long-term neurodevelopmental outcome in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery. Am J Obstet Gynecol 2007;196:231.e1–231.e4.
  61. Graef C, Ellenrieder B, Hecher K, Hackeloer BJ, Huber A, Bartmann P: Long-term neurodevelopmental outcome of 167 children after intrauterine laser treatment for severe twin-twin transfusion syndrome. Am J Obstet Gynecol 2006;194:303–308.
  62. Kiely J, Kiely M, Blickstein I: Contribution of the rise in multiple births to a potential increase in cerebral palsy. Pediatr Res 2000;47:314A.

    External Resources

  63. Blickstein I, Weissman A: Estimating the risk of cerebral palsy after assisted conceptions. N Engl J Med 1999;341:1313–1314.
  64. Derom C, Derom R, Vlietinck R, Maes H, Van den Berghe H: Iatrogenic multiple pregnancies in East Flanders, Belgium. Fertil Steril 1993;60:493–496.
  65. Helmerhorst FM, Perquin DA, Donker D, Keirse MJ: Perinatal outcome of singletons and twins after assisted conception: a systematic review of controlled studies. BMJ 2004;328:261–265.
  66. Jackson RA, Gibson KA, Wu YW, Croughan MS: Perinatal outcomes in singletons following in vitro fertilization: a meta-analysis. Obstet Gynecol 2004;103:551–563.
  67. Hvidtjorn D, Grove J, Schendel DE, Vaeth M, Ernst E, Nielsen LF, Thorsen P: Cerebral palsy among children born after in vitro fertilization: the role of preterm delivery – a population-based, cohort study. Pediatrics 2006;118:475–482.
  68. Pinborg A, Loft A, Schmidt L, Greisen G, Rasmussen S, Andersen AN: Neurological sequelae in twins born after assisted conception: controlled national cohort study. BMJ 2004;329:311–316.
  69. Stromberg B, Dahlquist G, Ericson A, Finnstrom O, Koster M, Stjernqvist K: Neurological sequelae in children born after in-vitro fertilisation: a population-based study. Lancet 2002;359:461–465.
  70. Ludwig AK, Sutcliffe AG, Diedrich K, Ludwig M: Post-neonatal health and development of children born after assisted reproduction: a systematic review of controlled studies. Eur J Obstet Gynecol Reprod Biol 2006;127:3–25.
  71. Goyen TA, Veddovi M, Lui K: Developmental outcome of discordant premature twins at 3 years. Early Hum Dev 2003;73:27–37.
  72. Einaudi MA, Busuttil M, Monnier AS, Chanus I, Palix C, Gire C: Neuropsychological screening of a group of preterm twins: comparison with singletons. Childs Nerv Syst 2008;24:225–230.
  73. Ronalds GA, De Stavola BL, Leon DA: The cognitive cost of being a twin: evidence from comparisons within families in the Aberdeen children of the 1950s cohort study. BMJ 2005;331:1306–1310.
  74. Posthuma D, De Geus EJ, Bleichrodt N, Boomsma DI: Twin-singleton differences in intelligence? Twin Res 2000;3:83–87.
  75. Christensen K, Petersen I, Skytthe A, Herskind AM, McGue M, Bingley P: Comparison of academic performance of twins and singletons in adolescence: follow-up study. BMJ 2006;333:1095–1097.
  76. Alin Akerman B, Hovmoller M, Radestad A, Thomassen PA: Physical and mental development in 4- to 6-year-old triplets. Acta Paediatr 1995;84:661–666.
  77. Feldman R, Eidelman AI: Does a triplet birth pose a special risk for infant development? Assessing cognitive development in relation to intrauterine growth and mother-infant interaction across the first 2 years. Pediatrics 2005;115:443–452.

 goto top of outline Author Contacts

Prof. Eric S. Shinwell, MD
Department of Neonatology, Kaplan Medical Center
PO Box 1, Rehovot 76100 (Israel)
Tel. +972 8944 1218, Fax +972 8944 1768
E-Mail eric_s@clalit.org.il


 goto top of outline Article Information

Presented at the International Symposium ‘Recent Advances in Neonatal Medicine’, Würzburg, 2008.

Published online: October 2, 2008
Number of Print Pages : 9
Number of Figures : 2, Number of Tables : 0, Number of References : 77


 goto top of outline Publication Details

Neonatology (Fetal and Neonatal Research)

Vol. 95, No. 1, Year 2009 (Cover Date: December 2008)

Journal Editor: Halliday H.L. (Belfast), Speer C.P. (Würzburg)
ISSN: 1661–7800 (Print), eISSN: 1661–7819 (Online)

For additional information: http://www.karger.com/NEO


Copyright / Drug Dosage / Disclaimer

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

Abstract

Outcomes, both short and long term, differ between singletons and multiplets. Recently, a number of large, well-designed studies have clarified these differences, particularly in light of major changes in perinatal and neonatal care that have influenced changing outcomes. Accordingly, this article will review risks for singletons, twins and higher-order multiples as whole groups and also after correction for gestational age and other potential confounding variables that differ markedly between the groups. In addition, we will focus on the effects of certain factors such as antenatal steroid therapy and gender. Finally, we will detail the specific long-term risks for multiples in terms of growth and neurodevelopmental disabilities.



 goto top of outline Author Contacts

Prof. Eric S. Shinwell, MD
Department of Neonatology, Kaplan Medical Center
PO Box 1, Rehovot 76100 (Israel)
Tel. +972 8944 1218, Fax +972 8944 1768
E-Mail eric_s@clalit.org.il


 goto top of outline Article Information

Presented at the International Symposium ‘Recent Advances in Neonatal Medicine’, Würzburg, 2008.

Published online: October 2, 2008
Number of Print Pages : 9
Number of Figures : 2, Number of Tables : 0, Number of References : 77


 goto top of outline Publication Details

Neonatology (Fetal and Neonatal Research)

Vol. 95, No. 1, Year 2009 (Cover Date: December 2008)

Journal Editor: Halliday H.L. (Belfast), Speer C.P. (Würzburg)
ISSN: 1661–7800 (Print), eISSN: 1661–7819 (Online)

For additional information: http://www.karger.com/NEO


Copyright / Drug Dosage

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

References

  1. Martin JA, Kung HC, Mathews TJ, Hoyert DL, Strobino DM, Guyer B, Sutton SR: Annual summary of vital statistics: 2006. Pediatrics 2008;121:788–801.
  2. Haklai T: Personal Communication. Department of Health Information, Ministry of Health, Israel, 2008.
  3. Fanaroff AA, Stoll BJ, Wright LL, Carlo WA, Ehrenkranz RA, Stark AR, Bauer CR, Donovan EF, Korones SB, Laptook AR, Lemons JA, Oh W, Papile LA, Shankaran S, Stevenson DK, Tyson JE, Poole WK: Trends in neonatal morbidity and mortality for very low birthweight infants. Am J Obstet Gynecol 2007;196:147.e1–147.e8.
  4. Report of the Expert Group on Multiple Births after IVF: One child at a time. Reducing multiple births after IVF. London, Human Fertilisation and Embryology Authority, 2006.
  5. Reichman B: Personal Communication. Israel VLBW Neonatal Database, 2007.
  6. Cheang CU, Huang LS, Lee TH, Liu CH, Shih YT, Lee MS: A comparison of the outcomes between twin and reduced twin pregnancies produced through assisted reproduction. Fertil Steril 2007;88:47–52.
  7. Martin JA, Park MM: Trends in twin and triplet births: 1980–1997. Natl Vital Stat Rep 1999;47:1–16.
  8. Luke B, Keith LG: The contribution of singletons, twins and triplets to low birth weight, infant mortality and handicap in the United States. J Reprod Med 1992;37:661–666.
  9. Imaizumi Y: Perinatal mortality in triplet births in Japan: time trends and factors influencing mortality. Twin Res 2003;6:1–6.
  10. Misra DP, Ananth CV: Infant mortality among singletons and twins in the United States during two decades: effects of maternal age. Pediatrics 2002;110:1163–1168.
  11. Alexander GR, Kogan M, Martin J, Papiernik E: What are the fetal growth patterns of singletons, twins, and triplets in the United States? Clin Obstet Gynecol 1998;41:114–125.
  12. Ballabh P, Kumari J, Al-Kouatly HB, Yih M, Arevalo R, Rosenwaks Z, Krauss AN: Neonatal outcome of triplet versus twin and singleton pregnancies: a matched case control study. Eur J Obstet Gynecol Reprod Biol 2003;107:28–36.
  13. Suri K, Bhandari V, Lerer T, Rosenkrantz TS, Hussain N: Morbidity and mortality of preterm twins and higher-order multiple births. J Perinatol 2001;21:293–299.
  14. Nielsen HC, Harvey-Wilkes K, MacKinnon B, Hung S: Neonatal outcome of very premature infants from multiple and singleton gestations. Am J Obstet Gynecol 1997;177:653–659.
  15. Maayan-Metzger A, Naor N, Sirota L: Comparative outcome study between triplet and singleton preterm newborns. Acta Paediatr 2002;91:1208–1211.
  16. Synnes AR, Ling EW, Whitfield MF, Mackinnon M, Lopes L, Wong G, Effer SB: Perinatal outcomes of a large cohort of extremely low gestational age infants (23–28 completed weeks of gestation). J Pediatr 1994;125:952–960.
  17. Buekens P, Wilcox A: Why do small twins have a lower mortality rate than small singletons? Am J Obstet Gynecol 1993;168:937–941.
  18. Ericson A, Gunnarskog J, Kallen B, Olausson PO: A registry study of very low birthweight liveborn infants in Sweden, 1973–1988. Acta Obstet Gynecol Scand 1992;71:104–111.
  19. Donovan EF, Ehrenkranz RA, Shankaran S, Stevenson DK, Wright LL, Younes N, Fanaroff AA, Korones SB, Stoll BJ, Tyson JE, Bauer CR, Lemons JA, Oh W, Papile LA: Outcomes of very low birth weight twins cared for in the National Institute of Child Health and Human Development Neonatal Research Network’s intensive care units. Am J Obstet Gynecol 1998;179:742–749.
  20. Shinwell ES, Blickstein I, Lusky A, Reichman B: Excess risk of mortality in very low birthweight triplets: a national, population-based study. Arch Dis Child Fetal Neonatal Ed 2003;88:F36–F40.
  21. Garite TJ, Clark RH, Elliott JP, Thorp JA: Twins and triplets: the effect of plurality and growth on neonatal outcome compared with singleton infants. Am J Obstet Gynecol 2004;191:700–707.
  22. Qiu X, Lee SK, Tan K, Piedboeuf B, Canning R: Comparison of singleton and multiple-birth outcomes of infants born at or before 32 weeks of gestation. Obstet Gynecol 2008;111:365–371.
  23. Friling R, Axer-Siegel R, Hersocovici Z, Weinberger D, Sirota L, Snir M: Retinopathy of prematurity in assisted versus natural conception and singleton versus multiple births. Ophthalmology 2007;114:321–324.
  24. Tyson JE, Parikh NA, Langer J, Green C, Higgins RD: Intensive care for extreme prematurity-moving beyond gestational age. N Engl J Med 2008;358:1672–1681.
  25. Blickstein I, Shinwell ES, Lusky A, Reichman B: Plurality-dependent risk of respiratory distress syndrome among very-low-birth-weight infants and antepartum corticosteroid treatment. Am J Obstet Gynecol 2005;192:360–364.
  26. Blickstein I, Reichman B, Lusky A, Shinwell ES: Plurality-dependent risk of severe intraventricular hemorrhage among very low birth weight infants and antepartum corticosteroid treatment. Am J Obstet Gynecol 2006;194:1329–1333.
  27. Shinwell ES, Reichman B, Lerner-Geva L, Boyko V, Blickstein I: ‘Masculinizing’ effect on respiratory morbidity in girls from unlike-sex preterm twins: a possible transchorionic paracrine effect. Pediatrics 2007;120:e447–e453.
  28. The ESHRE Capri Workshop Group: Multiple gestation pregnancy. Hum Reprod 2000;15:1856–1864.
  29. Blickstein I: Growth aberration in multiple pregnancy. Obstet Gynecol Clin North Am 2005;32:39–54.
  30. Buckler JM, Green M: Birth weight and head circumference standards for English twins. Arch Dis Child 1994;71:516–521.
  31. Ooki S, Yokoyama Y: Reference birth weight, length, chest circumference, and head circumference by gestational age in Japanese twins. J Epidemiol 2003;13:333–341.
  32. Dollberg G, Dollberg S: Fetal growth curves. Isr Med Assoc J 2006;8:518.
  33. Ooki S, Yokoyama Y: Physical growth charts from birth to six years of age in Japanese twins. J Epidemiol 2004;14:151–160.
  34. Estourgie-van Burk GF, Bartels M, van Beijsterveldt TC, Delemarre-van de Waal HA, Boomsma DI: Body size in five-year-old twins: heritability and comparison to singleton standards. Twin Res Hum Genet 2006;9:646–655.
  35. Buckler JM, Green M: The growth of twins between the ages of 2 and 9 years. Ann Hum Biol 2008;35:75–92.
  36. Karlberg J, Luo ZC: Foetal size to final height. Acta Paediatr 2000;89:632–636.
  37. Luke B, Leurgans S, Keith L, Keith D: The childhood growth of twin children. Acta Genet Med Gemellol (Roma) 1995;44:169–178.
  38. Keet MP, Jaroszewicz AM, Lombard CJ: Follow-up study of physical growth of monozygous twins with discordant within-pair birth weights. Pediatrics 1986;77:336–344.
  39. Monset-Couchard M, de Bethmann O, Relier JP: Long-term outcome of small versus appropriate size for gestational age co-twins/triplets. Arch Dis Child Fetal Neonatal Ed 2004;89:F310–F314.
  40. Ali MA, Ashizawa K, Kato S, Kouchi M, Koyama C, Hoshi H: Biological variables in height growth of Japanese twins: a comparison with those of singletons. Ann Hum Biol 2007;34:283–295.
  41. Luke B, Brown MB, Hediger ML, Misiunas RB, Anderson E: Perinatal and early childhood outcomes of twins versus triplets. Twin Res Hum Genet 2006;9:81–88.
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