Two studies support the practice of single blastocyst transfer.(News)

PHILADELPHIA -- Results of two U.S. studies may help dispel fears that single blastocyst transfer results in poor pregnancy success rates. The studies were presented at the annual meeting of the American Society for Reproductive Medicine.

Single blastocyst transfer, widely practiced in Europe, guarantees a reduction in multiple births, the biggest problem facing fertility specialists worldwide.

Although triplet pregnancies have been reduced dramatically in the United States by limiting the number of embryos transferred, twin pregnancies still make up roughly one-third of all births from assisted reproductive technology (ART).

The most recent figures from the Centers for Disease Control and Prevention show that in 2001 64% of ART births were singletons, 32% were twins, and almost 4% were triplets or other higher order multiples. More than three embryos were transferred in roughly 66% of the ART cycles.

Despite recent guidelines from the American Society for Reproductive Medicine (ASRM), which suggest consideration of single embryo transfer in patients with the most favorable prognosis (Fertil. Steril. 2004;82:773-4), there has been considerable resistance in the United States. Many physicians and patients fear that single embryo transfer may reduce overall pregnancy rates. The failure of an in vitro fertilization (IVF) cycle is a financial burden resting almost entirely on U.S. patients' shoulders. In contrast, the cost of IVF is covered by the national health care systems of most European countries.

Results of the two studies presented at the meeting may help change some opinions about the practice. "We feel strongly that single blastocyst transfer is the way to go," said Marius Meintjes, Ph.D., scientific director of assisted reproductive technology services at Presbyterian Hospital of Dallas.

He presented a 3-year retrospective study that examined live birth rates and twinning rates of 103 patients who had single blastocyst transfer (SBT) and 290 who had double blastocyst transfer (DBT). To be eligible for SBT, patients had to be 37 years of age or younger or be receiving donated oocytes. Patients had to have at least two excellent quality embryos to choose from on the day of transfer. The excess embryos were frozen, and if the patient failed to become pregnant during the fresh cycle, the clinic agreed to pay for subsequent frozen embryo cycles.