Correspondence

Cumulative Live-Birth Rates in a Trial of Single-Embryo or Double-Embryo Transfer

N Engl J Med 2009; 361:1812-1813October 29, 2009

Article

To the Editor:

We previously reported in the Journal 1 the results of a randomized, controlled trial comparing pregnancy outcomes in patients undergoing in vitro fertilization (IVF) involving a fresh single-embryo transfer followed, if no live birth occurred after the fresh-embryo cycle, by a frozen-thawed single-embryo transfer with patients undergoing IVF involving a fresh double-embryo transfer. As compared with the rates in the double-embryo-transfer group, in the single-embryo-transfer group, the live-birth rate was not substantially lower and the multiple-birth rate was significantly lower.1 Multiple birth is considered to be the main risk associated with IVF because of the increased rate of adverse perinatal outcomes.2,3

The present study investigated the cumulative live-birth rates in the two groups after the inclusion of all frozen-thawed cycles after the fresh-embryo cycle. The cumulative live-birth rate was defined as the number of women with a pregnancy resulting in at least one live birth divided by the number of women who underwent randomization. In the additional frozen-thawed cycles, one or two embryos were transferred, without regard to the original randomization group. All 661 patients who participated in the randomized trial were included; none of the patients were lost to follow-up, and all embryos were accounted for (Figure 1Figure 1Enrollment and Outcomes.).

The cumulative live-birth rates were 43.9% (145 of 330 patients) in the single-embryo-transfer group and 51.1% (169 of 331 patients) in the double-embryo-transfer group (difference, 7.1%; 95% confidence interval [CI], –0.6 to 14.8; P=0.08). The mean rate of live births was 53% (174 of 330 patients) in the single-embryo-transfer group and 57% (189 of 331 patients) in the double-embryo-transfer group (P=0.20). The multiple-birth rate was significantly lower in the single-embryo-transfer group than in the double-embryo-transfer group (2.3% vs. 27.5%; difference, 25.2%; 95% CI, 15.1 to 35.0; P<0.001). The rate of preterm birth (<37 full weeks of gestational age) was significantly higher in the double-embryo-transfer group as compared with the single-embryo-transfer group (25.5% vs. 11.8%; difference, 13.7%; 95% CI, 4.0 to 23.2; P<0.001) (see Table I in the Supplementary Appendix, available with the full text of this letter at NEJM.org).

The use of cumulative live-birth rates instead of outcome per cycle has advantages for the patient, since it better summarizes her chance of a live birth over an entire treatment period.4 We found that the cumulative live-birth rate after one oocyte retrieval was high in both groups. It was lower in the single-embryo-transfer group than in the double-embryo-transfer group, although not significantly so. The advantage of single-embryo transfer is the dramatically reduced rate of multiple births as compared with double-embryo transfer. A well-functioning cryopreservation program is a prerequisite to implementation of a single-embryo-transfer strategy and should be encouraged.5

Ann Thurin-Kjellberg, M.D., Ph.D.
Catharina Olivius, M.D.
Christina Bergh, M.D., Ph.D.
Gothenburg University, Gothenburg, Sweden
ann.thurin@vgregion.se

Supported by Sahlgrenska Academy, Sahlgrenska University Hospital, and the Göteborg Medical Society.

Dr. Thurin-Kjellberg reports receiving lecture fees from Merck Serono, Schering-Plough, and Ferring, and consulting fees from Merck Serono Sweden; and Dr. Bergh, lecture fees from Merck Serono, Schering-Plough, and Ferring. No other potential conflict of interest relevant to this letter was reported.

5 References

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   Full Text | Web of Science | Medline

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   Schieve LA, Meikle SF, Ferre C, Peterson HB, Jeng G, Wilcox LS. Low and very low birth weight in infants conceived with use of assisted reproductive technology. N Engl J Med 2002;346:731-737
   Full Text | Web of Science | Medline

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   Wennerholm UB, Bergh C. Outcome of IVF pregnancies. Fetal Matern Med Rev 2004;15:27-57
   CrossRef

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   Malizia BA, Hacker MR, Penzias AS. Cumulative live-birth rates after in vitro fertilization. N Engl J Med 2009;360:236-243
   Full Text | Web of Science | Medline

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   Veleva Z, Karinen P, Tomas C, Tapanainen J, Martikainen H. Elective single embryo transfer with cryopreservation improves the outcome and diminishes the costs of IVF/ICSI. Hum Reprod 2009;24:1632-1639
   CrossRef | Web of Science | Medline

Citing Articles (5)

Citing Articles

1. 1

   INGUNN JONSDOTTIR, KERSTI LUNDIN, CHRISTINA BERGH. (2011) Double embryo transfer gives good pregnancy and live birth rates in poor responders with a modest increase in multiple birth rates: results from an observational study. Acta Obstetricia et Gynecologica Scandinavica 90:7, 761-766
   CrossRef

2. 2

   Jacques P. Stassart, Romaine B. Bayless, Colleen L. Casey, William R. Phipps. (2011) Initial experience with a risk-sharing in vitro fertilization–embryo transfer program with novel features. Fertility and Sterility 95:7, 2192-2197
   CrossRef

3. 3

   Baris Ata, Bulent Urman. 2011. Infertility Treatment: Varying Approaches across Continents. , 175-182.
   CrossRef

4. 4

   Catharina Olivius, Christina Bergh. (2010) IVF: fewer complications with single-embryo transfer, but what about the live birth rates?. Expert Review of Obstetrics & Gynecology 5:4, 389-391
   CrossRef

5. 5

   Vasiliki A Moragianni, Alan S Penzias. (2010) Cumulative live-birth rates after assisted reproductive technology. Current Opinion in Obstetrics and Gynecology 22:3, 189-192
   CrossRef