Abstract
Objective
The objective of this systematic review and meta-analyses was to determine the risks
of preterm birth (PTB) and low birth weight (LBW) in twins conceived through in vitro fertilization (IVF) or IVF/intracytoplasmic sperm injection (ICSI) compared to spontaneously-conceived
twins after matching or controlling for at least maternal age.
Study design
The MOOSE guidelines for meta-analysis of observational studies were followed.
Search strategy
Medline and Embase were searched using comprehensive search strategies. Bibliographies
of identified articles were reviewed.
Selection criteria
English language studies of twins conceived by IVF or IVF/ICSI, compared with spontaneously
twins, that matched or controlled for at least maternal age.
Data collection and analysis
Two reviewers independently assessed titles, abstracts, articles and study quality
and extracted data. Statistical analyses were performed using the Review Manager (RevMan
5.0) software using a random effects model. Dichotomous data were meta-analyzed using
relative risks (RR) and continuous data with a weighted mean difference.
Results
Twelve studies were included which had a total of 4385 twins conceived after IVF or
IVF/ICSI (one stillbirth was excluded) and 11,793 spontaneously-conceived twins. After
matching or controlling for maternal age and often other factors, compared to spontaneously-conceived
twins, IVF twins had increased risks of both our primary outcomes: PTB (RR 1.23, 95%
CI 1.09, 1.41) and LBW (<2500 g, RR 1.14, 95% CI 1.06, 1.22). They were at increased risk for PTB <32–33 weeks (RR
1.63, 95% CI 1.17, 2.27) although the risks of late PTB (32–36 weeks, RR 1.12, 95%
CI 0.85, 1.47), very LBW (<1500 g, RR 1.28, 95% CI 0.73, 2.24), extremely LBW (<1000 g, RR 0.88, 0.04, 19.40), intrauterine growth restriction (RR 1.06, 95% CI 0.72, 1.55)
and the difference in the duration of gestation (−0.5 weeks, 95% CI −1.2 weeks, 0.2
weeks) were not statistically significantly increased compared to spontaneously-conceived
twins. IVF twins had significantly lower mean birth weights (−105 g, 95% CI −204 g, −3 g).
Conclusions
IVF twins have small but significantly increased risks of PTB, LBW, and lower mean
birth weight compared to spontaneously-conceived twins after matching or controlling
for at least maternal age.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to European Journal of Obstetrics and Gynecology and Reproductive BiologyAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Birth after the reimplantation of a human embryo.Lancet. 1978; 2: 366
- Perinatal care in Canada.BMC Womens Health. 2004; 4: S28
- Births: final data for 2004.Natl Vital Stat Rep. 2006; 55: 1-101
Assisted reproductive technologies hit all time high [editorial]. The Lancet 2006; 368 (9529):2.
- Pregnancy outcomes after assisted reproductive technology.J Obstet Gynaecol Can. 2006; 28: 220-250
- Assisted reproductive technologies in Canada: 2005 results from the Canadian Assisted Reproductive Technologies Register.Fertil Steril. 2008; : 2008
- Perinatal outcomes of in vitro fertilization twins: a systematic review and meta-analyses.Am J Obstet Gynecol. 2005; 193: 141-152
Liu S, Allen A, and Fraser W. Fetal and Infant Health Outcomes. Chapter 20 Preterm Birth Rate, 123–132. 2008. Public Health Agency of Canada, Ottawa, Ontario. Canadian Perinatal Health Report. Ref Type: Report.
- Determinants of low birth weight: methodological assessment and meta-analysis.Bull World Health Organ. 1987; 65: 663-737
- Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis of observational studies in epidemiology (MOOSE) group.JAMA. 2000; 283: 2008-2012
- Comparison of mortality between private for-profit and private not-for-profit hemodialysis centers: a systematic review and meta-analysis.JAMA. 2002; 288: 2449-2457
- Measuring inconsistency in meta-analyses.BMJ. 2003; 327: 557-560
- Obstetric outcome among women with unexplained infertility after IVF: a matched case-control study.Hum Reprod. 2002; 17: 1755-1761
- Neonatal outcome and congenital malformations in children born after in-vitro fertilization. [comment].Hum Reprod. 2002; 17: 1391-1398
- Perinatal outcome of twin pregnancies after in vitro fertilization.Acta Obstet Gynecol Scand. 2004; 83: 1079-1084
- The outcome of twin pregnancies after IVF.Hum Reprod. 1998; 13: 1702-1705
- Pregnancy outcome in spontaneous twins versus twins who were conceived through in vitro fertilization.Am J Obstet Gynecol. 2003; 189: 513-518
- Pregnancy complications, obstetric risks, and neonatal outcome in singleton and twin pregnancies after GIFT and IVF.Arch Gynecol Obstet. 2003; 268: 256-261
- High frequency of cesarean section, antepartum hemorrhage, placenta previa, and preterm delivery in in-vitro fertilization twin pregnancies [8].Fertil Steril. 2003; 80: 666-668
- Obstetric outcome of in vitro fertilization pregnancies compared with normally conceived pregnancies.Am J Obstet Gynecol. 1992; 167: 778-784
- Preterm birth in twins after subfertility treatment: population based cohort study.BMJ. 2005; 331: 1173
- Obstetric and perinatal outcome of children conceived from cryopreserved embryos.Hum Reprod. 1997; 12: 1819-1825
- Danish national in-vitro fertilization registry 1994 and 1995: a controlled study of births, malformations and cytogenetic findings.Hum Reprod. 1999; 14: 1896-1902
- Dilemma of increased obstetric risk in pregnancies following IVF-ET.J Assisted Reprod Genet. 2003; 20: 216-221
- Changing patterns of low birth weight and preterm birth in the United States, 1981–1998.Paediatr Perinat Epidemiol. 2002; 16: 8-15
- IVF results in de novo DNA methylation and histone methylation at an Igf2-H19 imprinting epigenetic switch.Mol Hum Reprod. 2005; 11: 631-640
- Elevated maternal serum relaxin concentrations throughout pregnancy in singleton gestations after superovulation.Obstet Gynecol. 1998; 92: 17-20
- Monozygotic twinning following assisted conception: an analysis of 81 consecutive cases.Hum Reprod. 2003; 18: 1937-1943
- Perinatal outcome of singletons and twins after assisted conception: a systematic review of controlled studies.BMJ. 2004; 328: 261
Peters J, Mengersen K. Selective reporting of adjusted estimates in observational epidemiology studies: reasons for implications for meta-analyses. Evaluation and the Health Professions 2008;published on line November 9, 2008 as doi:10.1177/0163278708324438.
Article info
Publication history
Published online: October 05, 2009
Accepted:
September 16,
2009
Received in revised form:
July 30,
2009
Received:
February 10,
2009
Identification
Copyright
© 2009 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
