The promise of single-embryo transfer

Multiple-gestation pregnancies after assisted reproductive technology treatment: population trends and future directions

Assisted reproductive technology (ART) treatments, such as in vitro fertilization, have benefited many couples worldwide. However, ART as currently practiced, with the usual transfer of at least two embryos, poses sizable risks for multiple-gestation pregnancy and accompanying serious maternal and child health sequelae. While limiting the number of embryos transferred would appear a straightforward solution, treatments with single-embryo transfer are rare. Likely reasons for this include patient and provider desires to maximize the chance for success in a single treatment given the high cost and lack of insurance coverage, the (sometimes mistaken) belief that transferring more embryos will increase the chance for pregnancy, and the preference for multiple births among some women undergoing ART. Although recent population-based data in the USA and Europe suggest the number of embryos transferred is decreasing, the ART multiple-birth rate remains high. Comprehensive patient-education efforts and continued research on the efficacy of single-embryo transfer are needed.

Eliminating multiple pregnancies: an appropriate target for government intervention?

The manuscript in this issue of the journal by Bissonette et al. reports on a new government-sponsored intervention into the practice of IVF within the province of Quebec, Canada, which in the authors' opinion highly successfully reduced twinning rates, while maintaining overall acceptable pregnancy rates. Given the opportunity to comment, their manuscript, in my opinion, only reemphasizes why, despite wide professional support, the concept of single embryo transfer (SET) is: (i) damaging to most infertility patients by reducing pregnancy chances; (ii) does so without compensatory benefits; (iii) impinges on patients' rights to self-determination; (iv) has significant negative impact on IVF-generated birth rates; and (v) thus, demonstrating, once more, that governments should not interfere with the patient-physician relationships.

Ovarian stimulation retards postimplantation development and alters global gene expression profile of blastocysts in mouse

This study compares the quality, developmental capacity and global gene expression profile of embryos generated from superovulated and natural cycles. We found that ovarian stimulation impaired quality of blastocysts (cell number: 68.9 +/- 6.9 vs. 76.8 +/- 7.9; diameter of blastocysts: 145.3 +/- 76.9 microm vs. 152.6 +/- 65.5 microm), fetus development (rate of development to term: 45.5% vs. 69.1%; weight of 18.5-dpc fetuses: 1.23 +/- 0.03 g vs. 1.34 +/- 0.03 g) and caused 92 genes differentially expressed.

A randomized controlled study of human serum albumin and serum substitute supplement as protein supplements for IVF culture and the effect on live birth rates

BACKGROUND

It has been speculated that the addition of proteins more complex than human serum albumin (HSA) to culture media may improve IVF outcomes. Whether the expense, labor and risk of adding additional human-derived protein to IVF media are warranted is a question unanswered.

METHODS

In a randomized controlled trial with couples undergoing routine IVF or ICSI, 528 patients were assigned to one of two treatment groups. Embryos were cultured in either media supplemented with HSA as a solitary protein supplement or in media supplemented with HSA+serum substitute supplement (SSS) from the 2PN stage until the time of embryo transfer. Clinical end-points monitored included implantation (total 1151 embryos) and live birth rates (total 528 patients).

RESULTS

The transfer of embryos cultured in HSA+SSS resulted in higher embryo implantation (289/571, 50.6% versus 254/580, 43.8%; difference 6.8% with 95% CI 1.0-12.7, P = 0.042) and live birth rates (167/266, 62.8% versus 142/262, 54.2%; difference 8.6% with 95% CI 0.1-17.3, P = 0.043) when compared with those of women whose embryos were cultured with HSA as the sole protein supplement.

CONCLUSIONS

SSS added to commercial HSA-supplemented embryo culture media resulted in an overall increase in implantation and live birth rates. It remains uncertain whether the use of human-derived blood products in culture media and the requirement for ultra-rigorous quality control measures make these findings applicable to the average IVF laboratory. Protein enrichment of media may significantly improve the blastocyst implantation rate, creating opportunities to transfer single blastocysts without compromising the live birth rate. The study was registered at clinicaltrials.gov. NCT00708383.

Phase-subtraction cell-counting method for live mouse embryos beyond the eight-cell stage

Since 1978 in vitro fertilization (IVF) procedures have resulted in the birth of over 3 million babies. Yet in 2005, IVF procedures had a live birth rate of only 34%, with 32% of these births resulting in multiple pregnancies. These multiple pregnancies were directly attributed to the transfer of multiple embryos to increase the probability that a single, healthy embryo was included. The predominantly accepted noninvasive viability markers for embryos created by IVF are (1) number of cells at specific time points during development and (2) overall morphology of the embryo. Currently, it is difficult to count the number of cells beyond the eight-cell stage noninvasively. We report a nontoxic cell-counting method capable of counting cell numbers ranging from 8 to 26 in live mouse embryos. This method is derived from the fusion of differential interference contrast and optical quadrature microscopy and is verified by epifluorescence images of Hoechst-stained nuclei. The phase-subtraction cell-counting method is the first accurate, nontoxic technique to count cells through the morula stage in mouse embryos and may enhance the use of cell number as a viability marker if adopted for use with human embryos in the IVF clinic.

A mandatory single blastocyst transfer policy with educational campaign in a United States IVF program reduces multiple gestation rates without sacrificing pregnancy rates

OBJECTIVE

To reduce the twin rate in our IVF program.

DESIGN

A prospective educational study of infertile couples; a retrospective review of IVF outcomes before vs. after mandatory single embryo transfer (mSBT) policy change.

SETTING

University-based infertility center.

PATIENT(S)

One hundred ten of 120 consecutive new infertile couples completed the educational study. Outcomes of all embryo transfers (n = 693) performed 17 months before and 17 months after mSBT were evaluated.

INTERVENTION(S)

A 1-page educational summary of comparative risks of twins vs. singletons to maternal and child health.

MAIN OUTCOME MEASURE(S)

Knowledge of twin risks and desired number of embryos transferred before and after education. Pregnancy rates, number of embryos transferred, and multiple-gestation rates before and after mSBT policy.

RESULT(S)

After education, knowledge of twin risks improved and a significant number of subjects changed their desired outcome to a lower gestational number. There was no change in ongoing pregnancy rates with blastocyst transfer before and after mSBT (63% vs. 58%; NS). Program-wide number of embryos transferred (2.1 +/- 0.6 vs. 1.9 +/- 0.7) and multiple-gestation rates (35% vs. 19%) decreased significantly while pregnancy rates were maintained.

CONCLUSION(S)

Simple educational materials can improve knowledge of twin pregnancy risks and affect decision making. In high-risk patients, mSBT results in pregnancy rates similar to two-blastocyst transfer, with decreased twin rates.

Day-3 embryo morphology predicts euploidy among older subjects

OBJECTIVE

To evaluate whether day-3 embryo morphology predicts euploidy.

DESIGN

Retrospective.

SETTING

Private IVF center.

PATIENT(S)

Subjects (n = 144) undergoing in vitro fertilization and preimplantation genetic diagnosis (PGD).

INTERVENTION(S)

Translate day-3 embryo characteristics into a standardized score.

MAIN OUTCOME MEASURE(S)

Day-3 embryo morphology score and PGD fluorescence in situ hybridization results for chromosomes: 13, 15, 16, 17, 18, 21, 22, X, and Y.

RESULT(S)

Of 1,043 biopsied blastomeres, 67% (n = 696) were chromosomally abnormal. Women with advanced maternal age (AMA) were 1.3 times more likely to have chromosomal errors (95% CI 1.1-1.4) than younger subjects (<38 years old). Morphology predicted PGD results in the AMA group (n = 553), but not in younger women. Fragmentation predicted euploidy in both the younger and the AMA group, but cell number did not.

CONCLUSION(S)

Day-3 embryo morphology selects for euploidy among AMA subjects but not among younger women who may have other factors responsible for embryo dysmorphism. However, cellular fragmentation is a sensitive proxy for selecting chromosomally normal embryos in both age groups. It is unclear that PGD-aneuploidy screening is a better tool for selecting which embryos to transfer than the standard approach of using day-3 embryo features, particularly among older women, a group for whom this technology is targeted.

A 47-year-old woman with fertility problems who desires a multiple pregnancy

Mrs Z is a 47-year-old woman with long-standing infertility who is about to undergo in vitro fertilization (IVF) using donor oocytes from an anonymous donor. She has already undergone an IVF cycle with her own oocytes and an IVF cycle using donor oocytes from a known donor without a successful pregnancy. Mrs Z has been advised by her infertility physician to consider the transfer of a single embryo, but she does not wish to decrease her likelihood of conception, and, after her long and expensive infertility saga, wishes to conceive twins. The science of IVF has evolved significantly in the last several years, increasing the likelihood of successful pregnancy and reducing the need to transfer more than 1 embryo with its inherent risks of multiple pregnancy. The state of the science and why patients may continue to want multiple embryos transferred, including costs and lack of insurance coverage for infertility treatments, are discussed.