Two consecutive singleton pregnancies versus one twins pregnancy as preferred outcome of in vitro fertilization for mothers and infants: a retrospective case-control study

Single-embryo transfer: a key strategy to reduce the risk for multiple pregnancy in assisted human reproduction

In the early days of assisted reproductive technology (ART), the main target was achieving gestation. Success rates were low, and multiple embryo transfers became common practice, with multiple pregnancies being 20 times higher than in natural conception. Multiple pregnancy is associated with a higher risk of complications for the mother and the baby than a singleton pregnancy. Added to healthcare costs, multiple pregnancy also involves other costs and psychosocial risks, with a high social and health costs. At present, success rates of assisted human reproduction (AHR) have improved dramatically, partially due to advances in laboratory techniques such as culture of blastocyst-stage embryos and vitrification. Additionally, there is a wide range of counseling, health and economic policies that have demonstrated being effective in increasing single-embryo transfer (SET) practices and reducing multiple pregnancies, which ensures satisfactory success rates. Therefore, single-embryo transfer emerges as the approach of choice for AHR to result in a full-term healthy newborn.

Believing that transferring more embryos will result in increased pregnancy rates: a flawed concept: a SWOT analysis

A belief exists that transferring multiple embryos can improve pregnancy rates. However, this concept is flawed. Multiple factors affect outcomes when transferring embryos, endometrial receptivity, and rates of aneuploidy among them. In this article, we will discuss how factors can affect outcomes at IVF that are independent of the number of embryos transferred. It is important to understand the role of accessory factors on pregnancy rates to be able to counsel patients as per the number of embryos that should be transferred. An understanding of this concept will also lead to a realistic understanding of how multiple embryo transfers may result in better cumulative pregnancy rates than a single transfer of multiple embryos. Finally, we will present a SWOT analysis diagram to help guide clinical decision-making.

Is a Blanket Elective Single Embryo Transfer Policy Defensible?

For the purpose of reducing maternal and neonatal morbidity, elective single transfer (eSET) in in vitro fertilization (IVF) was first proposed in 1999. The purpose of this review is to summarize recent oral debate between a proponent and an opponent of expanded eSET utilization in an attempt to determine whether a blanket eSET policy, as is increasingly considered, is defensible. While eSET is preferable when possible, and agreed upon by provider and patient, selective double embryo transfer (DET) must be seriously entertained if deemed more appropriate or is desired by the patient. Patient autonomy, let alone prolonged infertility and advancing age, demand nothing less. Importantly, IVF-generated twins represent only 15.7% of the national twin birth rate in the United States. Non-IVF fertility treatments have been identified as the main cause of all multiple births for quite some time. However, educational and regulatory efforts over the last decade, paradoxically, have exclusively only been directed at the practice of IVF, although IVF patient populations are rapidly aging. It is difficult to understand why non-IVF fertility treatments, usually applied to younger women, have so far escaped attention. This debate on eSET utilization in association with IVF may contribute to a redirection of priorities.

Deciding how many embryos to transfer: ongoing challenges and dilemmas

Despite the risks associated with twin and higher-order multiple births, and calls in many countries for single-embryo transfer as the standard of care for good-prognosis patients, providers frequently transfer additional embryos, raising critical questions as to why this is the case and what can be done about it. In-depth interviews of approximately 1 h each were conducted with 27 IVF providers (17 physicians and 10 other healthcare providers) and 10 patients. Professional guidelines often contain flexibility and ambiguities or are unenforced. Thus, both providers and patients frequently wrestle with several dilemmas. Decisions about the number of embryos to transfer emerge as dyadic, dynamic and affected by several factors (e.g. providers' type of institution, and personal and professional experiences and perceptions of the data), leading to differences in whether, how and with what effectiveness clinicians address these issues with patients. Many clinicians feel that the evidence concerning the apparent increased risk associated with a twin birth is not 'compelling', and patients frequently minimize the hazards. These data, the first to explore several critical aspects of how providers and patients view and make decisions about the number of embryos to transfer, thus highlight tensions, uncertainties and challenges that providers and patients confront, and have key implications for future practice, research, policy and education.

Proof of concept: preimplantation genetic screening without embryo biopsy through analysis of cell-free DNA in spent embryo culture media

OBJECTIVE

To assess whether preimplantation genetic screening (PGS) is possible by testing for free embryonic DNA in spent IVF media from embryos undergoing trophectoderm biopsy.

DESIGN

Prospective cohort analysis.

SETTING

Academic fertility center.

PATIENT(S)

Seven patients undergoing IVF and 57 embryos undergoing trophectoderm biopsy for PGS.

INTERVENTION(S)

On day 3 of development, each embryo was placed in a separate media droplet. All biopsied embryos received a PGS result by array comparative genomic hybridization. Preimplantation genetic screening was performed on amplified DNA extracted from media and results were compared with PGS results for the corresponding biopsy.

MAIN OUTCOME MEASURE(S)

[1] Presence of DNA in spent IVF culture media. [2] Correlation between genetic screening result from spent media and corresponding biopsy.

RESULT(S)

Fifty-five samples had detectable DNA ranging from 2-642 ng/μL after a 2-hour amplification. Six samples with the highest DNA levels underwent PGS, rendering one result with a derivative log ratio SD (DLRSD) of <0.85 (a quality control metric of oligonucleotide array comparative genomic hybridization). The fluid sample and trophectoderm results were identical demonstrating (45XY, -13). Three samples were reamplified 1 hour later and tested showing improving DLRSD. One of the three samples with a DLRSD of 0.85 demonstrated (46XY), consistent with the biopsy. Overnight DNA amplification showed DNA in all samples.

CONCLUSION(S)

We demonstrate two novel findings: the presence of free embryonic DNA in spent media and a result that is consistent with trophectoderm biopsy. Improvements in DNA collection, amplification, and testing may allow for PGS without biopsy in the future.

Risks of spontaneously and IVF-conceived singleton and twin pregnancies differ, requiring reassessment of statistical premises favoring elective single embryo transfer (eSET)

A published review of the literature by Dutch investigators in 2004 suggested significant outcome differences between spontaneously - and in vitro fertilization (IVF) - conceived singleton and twin pregnancies. Here we review whether later studies between 2004-2015 confirmed these findings. Though methodologies of here reviewed studies varied, and all were retrospective, they overall confirmed results of the 2004 review, and supported significant outcome variances between spontaneously- and IVF-conceived pregnancies: IVF singletons demonstrate significantly poorer and IVF twins significantly better perinatal outcomes than spontaneously conceived singletons and twins, with differences stable over time, and with overall obstetrical outcomes significantly improved. Exaggerations of severe IVF twin risks are likely in the 50 % range, while exaggerations of milder perinatal risks are approximately in 25 % range. Though elective single embryo transfers (eSET) have been confirmed to reduce pregnancy chances, they are, nevertheless, increasingly utilized. eSET, equally unquestionably, however, reduces twin pregnancies. Because twin pregnancies have been alleged to increase outcome risks in comparison to singleton pregnancies, here reported findings should affect the ongoing discussion whether increased twin risks are factual. With no risk excess, eSET significantly reduces IVF pregnancy chances without compensatory benefits and, therefore, is not advisable in IVF, unless patients do not wish to conceive twins or have medical contraindications to conceiving twins.