Increasing twinning rates in Norway, 1967–2004: the influence of maternal age and assisted reproductive technology (ART)

References

• 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(7434)261
   PubMed Web of Science ®Google Scholar
• Pinborg A, Loft A, Nyboe Andersen A. Neonatal outcome in a Danish national cohort of 8602 children born after in vitro fertilization or intracytoplasmic sperm injection: the role of twin pregnancy. Acta Obstet Gynecol Scand 2004; 83(11)1071–8
   PubMed Web of Science ®Google Scholar
• Westergaard T, Wohlfahrt J, Aaby P, Melbye M. Population based study of rates of multiple pregnancies in Denmark, 1980–94. BMJ 1997; 314(7083)775–9
   PubMed Web of Science ®Google Scholar
• 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(7461)311
   PubMed Web of Science ®Google Scholar
• 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(9305)461–5
   PubMed Web of Science ®Google Scholar
• Senat MV, Ancel PY, Bouvier-Colle MH, Breart G. How does multiple pregnancy affect maternal mortality and morbidity?. Clin Obstet Gynecol 1998; 41(1)78–83
   PubMed Web of Science ®Google Scholar
• Pinborg A, Loft A, Schmidt L, Langhoff-Roos J, Andersen AN. Maternal risks and perinatal outcome in a Danish national cohort of 1005 twin pregnancies: the role of in vitro fertilization. Acta Obstet Gynecol Scand 2004; 83(1)75–84
   PubMed Web of Science ®Google Scholar
• Imaizumi Y. A comparative study of zygotic twinning and triplet rates in eight countries, 1972–1999. J Biosoc Sci 2003; 35(2)287–302
   PubMed Web of Science ®Google Scholar
• Fellmann J, Eriksson A. Variations in the maternal age effect on twinning rates: the Nordic experience. Twin Res Hum Genet 2005; 8(5)515–23
   PubMed Web of Science ®Google Scholar
• Central Bureau of Statistics. Available on WWW at: http://www.ssb.no/aarbok/tab/tab-068.html.
   Google Scholar
• Irgens LM. The Medical Birth Registry of Norway. Epidemiological research and surveillance throughout 30 years. Acta Obstet Gynecol Scand 2000; 79(6)435–9
   PubMed Web of Science ®Google Scholar
• The Directorate for Social and Health Affairs. Available on WWW at: http://www.shdir.no.
   Google Scholar
• The Medical Birth Registry of Norway. Available on WWW at: http://www.mfr.no.
   Google Scholar
• Romundstad LB, Romundstad PR, Sunde A, von During V, Skjaerven R, Vatten LJ. Increased risk of placenta previa in pregnancies following IVF/ICSI; a comparison of ART and non-ART pregnancies in the same mother. Hum Reprod 2006; 21(9)2353–8
   PubMed Web of Science ®Google Scholar
• von During V, Maltau JM, Forsdahl F, Abyholm T, Kolvik R, Ertzeid G, et al. [Pregnancy, births and infants after in-vitro-fertilization in Norway, 1988–1991]. Tidsskr Nor Laegeforen 1995; 115(17)2054–60
   PubMedGoogle Scholar
• Weinberg W. Beiträge zur Physiologie und Pathologie der Mehrlingsgeburthen beim Menschen. Arch Gesamte PhysiolMenschen Tiere 1902; 88: 346–430
   Google Scholar
• Pinborg A, Loft A, Schmidt L, Andersen AN. Attitudes of IVF/ICSI-twin mothers towards twins and single embryo transfer. Hum Reprod 2003; 18(3)621–7
   PubMed Web of Science ®Google Scholar
• The Norwegian Institute of Public Health. Available on WWW at: http://www.fhi.no.
   Google Scholar
• Bolton P, Yamashita Y, Farquhar CM. Role of fertility treatments in multiple pregnancy at National Women's Hospital from 1996 to 2001. Aust N Z J Obstet Gynaecol 2003; 43(5)364–8
   PubMed Web of Science ®Google Scholar
• Beemsterboer SN, Homburg R, Gorter NA, Schats R, Hompes PG, Lambalk CB. The paradox of declining fertility but increasing twinning rates with advancing maternal age. Hum Reprod 2006; 21(6)1531–2
   PubMed Web of Science ®Google Scholar
• Hall JG. Twinning. Lancet 2003; 362(9385)735–43
   PubMed Web of Science ®Google Scholar
• Midthjell K, Kruger O, Holmen J, Tverdal A, Claudi T, Bjorndal A, et al. Rapid changes in the prevalence of obesity and known diabetes in an adult Norwegian population. The Nord-Trondelag Health Surveys: 1984–1986 and 1995–1997. Diabetes Care 1999; 22(11)1813–20
   PubMed Web of Science ®Google Scholar
• Basso O, Nohr EA, Christensen K, Olsen J. Risk of twinning as a function of maternal height and body mass index. JAMA 2004; 291(13)1564–6
   PubMed Web of Science ®Google Scholar
• Reddy UM, Branum AM, Klebanoff MA. Relationship of maternal body mass index and height to twinning. Obstet Gynecol 2005; 105(3)593–7
   PubMed Web of Science ®Google Scholar
• Gerris JM. Single embryo transfer and IVF/ICSI outcome: a balanced appraisal. Hum Reprod Update 2005; 11(2)105–21
   PubMed Web of Science ®Google Scholar
• Thurin A, Hausken J, Hillensjo T, Jablonowska B, Pinborg A, Strandell A, et al. Elective single-embryo transfer versus double-embryo transfer in in vitro fertilization. N Engl J Med 2004; 351(23)2392–402
   PubMed Web of Science ®Google Scholar