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Risk of Adverse Perinatal Outcomes in Dizygotic Twins After IVF Pregnancies: A Systematic Review

1 February 2011


Background: Since the birth of the first test tube baby, 25 years ago, more than three million babies have been born using assisted reproductive technologies (ART). Twin births by way of ART represent 20-30% of U.S. and European births, as compared to only 1% of natural births. The purpose of this study is to investigate the risk of adverse perinatal outcomes in ART dizigotic twins, compared with non-ART twins.

Method: A review of the medical literature available in Pub Med, EBM review, the National Clinical Trials Registry and CINAHL databases. The search was limited to English language sources between 2000 and 2010. Three cohort studies were identified for the final systematic review. The GRADE tool was used to evaluate the evidence.

Results: The three cohort studies found no higher risk of low birth weight in ART twins after stratification for maternal age and parity. Birth weight discordance and mortality rates showed similar result as low birth weight. Two of the studies found an increased risk of hospitalization and neonatal intensive care unit admissions and maintained this result after stratification for maternal factors. One study found a higher risk of prematurity in twins conceived by in vitro fertilization; no such association was found in the other study.

Conclusion: A review of the evidence found an increased risk of adverse perinatal outcome in twins conceived by in vitro fertilization, compared with twin not conceived by in vitro fertilization. However, no statistically significance differences were found after stratification for maternal confounders, with the exception of hospital and NICU admission. The grade for all outcomes was moderate.


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