Preterm birth and low birth weight among in vitro fertilization twins: A systematic review and meta-analyses

McDonald, Sarah D.; Han, Zhen; Mulla, Sohail; Ohlsson, Arne; Beyene, Joseph; Murphy, Kellie E.; on behalf of the Knowledge Synthesis Group,

doi:10.1016/j.ejogrb.2009.09.019

« Previous Next »European Journal of Obstetrics & Gynecology and Reproductive Biology
Volume 148, Issue 2 , Pages 105-113, February 2010

Preterm birth and low birth weight among in vitro fertilization twins: A systematic review and meta-analyses

Sarah D. McDonald
- Division of Maternal-Fetal Medicine, Departments of Obstetrics & Gynecology, Diagnostic Imaging, and Clinical Epidemiology and Biostatistics, McMaster University, 1200 Main St. West, HSC 3N52B, Hamilton, ON L8N 3Z5, Canada
- Corresponding author. Tel.: +1 905 525 9140x26622; fax: +1 905 524 2911.
Zhen Han
- Department of Obstetrics and Gynecology, First Affiliated Hospital of Xi’an Jiao Tong University, Shaanxi Province, PR China
Sohail Mulla
- Faculty of Health Sciences, McMaster University, Hamilton, Canada
Arne Ohlsson
- Department of Paediatrics, and Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada
- Department of Obstetrics and Gynecology, Mount Sinai Hospital and the University of Toronto, Toronto, Ontario, Canada
Joseph Beyene
- Program in Population Health Sciences, Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada
Kellie E. Murphy
- Department of Obstetrics and Gynecology, Mount Sinai Hospital and the University of Toronto, Toronto, Ontario, Canada
on behalf of the Knowledge Synthesis Group
- Members of Knowledge Synthesis Group on determinants of low birth weight/preterm birth:Prakesh Shah: Assistant Professor, Department of Paediatrics, Mount Sinai Hospital and Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, CanadaArne Ohlsson: Professor Emeritus, Department of Paediatrics, Mount Sinai Hospital and Departments of Paediatrics, Obstetrics and Gynaecology, and Health Policy, Management and Evaluation, University of Toronto, CanadaVibhuti Shah: Associate Professor, Department of Paediatrics, Mount Sinai Hospital and Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, CanadaKellie E Murphy: Associate Professor, Department of Obstetrics and Gynecology, Mount Sinai Hospital and University of Toronto, CanadaSarah D McDonald: Assistant Professor, Division of Maternal-Fetal Medicine, Departments of Obstetrics & Gynecology and Diagnostic Imaging, and Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, CanadaEileen Hutton: Associate Professor, Department of Obstetrics and Gynecology, McMaster University, Hamilton, CanadaChristine Newburn-Cook: Associate Professor & Associate Dean Research, Faculty of Nursing, University of Alberta, Edmonton, CanadaCorine Frick: Director, Alberta Perinatal Health Program and Adjunct Professor, Faculty of Nursing, University of Calgary, Calgary, CanadaFran Scott: Associate Professor, Dalla Lana School of Public Health, University of Toronto and Toronto Public Health, Toronto, CanadaVictoria Allen: Associate Professor, Department of Obstetrics and Gynaecology, Dalhousie University, Halifax, CanadaJoseph Beyene: Assistant Professor, Research Institute of The Hospital for Sick Children and Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.

Received 10 February 2009; received in revised form 30 July 2009; accepted 16 September 2009. published online 05 October 2009.

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 (<2500g, 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 (<1500g, RR 1.28, 95% CI 0.73, 2.24), extremely LBW (<1000g, 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 (−105g, 95% CI −204g, −3g).

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: In vitro fertilization, Low birth weight, Preterm birth, Twin, Meta-analysis