Commentary: Is elective single embryo transfer a cost-effective alternative to double embryo transfer?

Magnitude and significance of the peak of early embryonic mortality

Embryonic development is of great importance because it determines congenital anomalies and influences their severity. However, little is known about the actual probabilities of success or failure and about the nature of early embryonic defects. Here, we propose that the analysis of embryonic mortality as a function of post-fertilization time provides a simple way to identify major defects. By reviewing the literature, we show that even small initial defects, e.g., spatial cellular asymmetries or irregularities in the timing of development, carry with them lethal effects in subsequent stages of embryogenesis. Although initially motivated by human study, in this contribution, we review the few embryonic mortality data available for farm animals and highlight zebrafish as a particularly suited organism for such a kind of study because embryogenesis can be followed from its very beginning and observed easily thanks to eggshell transparency. In line with the few other farm animals for which data are available, we provide empirical evidence that embryonic mortality in zebrafish has a prominent peak shortly after fertilization. Indeed, we show how subsequent mortality rates decay according to a power law, supporting the role of the early embryonic mortality peak as a screening process rapidly removing defective embryos.

Cost-effectiveness analysis of different embryo transfer strategies in England

OBJECTIVE

The objective of this study was to assess the cost-effectiveness of different embryo transfer strategies for a single cycle when two embryos are available, and taking the NHS cost perspective.

DESIGN

Cost-effectiveness model.

SETTING

Five in vitro fertilisation (IVF) centres in England between 2003/04 and 2004/05.

POPULATION

Women with two embryos available for transfer in three age groups (<30, 30-35 and 36-39 years).

METHODS

A decision analytic model was constructed using observational data collected from a sample of fertility centres in England. Costs and adverse outcomes are estimated up to 5 years after the birth. Incremental cost per live birth was calculated for different embryo transfer strategies and for three separate age groups: less than 30, 30-35 and 36-39 years.

MAIN OUTCOME MEASURES

Premature birth, neonatal intensive care unit admissions and days, cerebral palsy and incremental cost-effectiveness ratios.

RESULTS

Single fresh embryo transfer (SET) plus frozen single embryo transfer (fzSET) is the more costly in terms of IVF costs, but the lower rates of multiple births mean that in terms of total costs, it is less costly than double embryo transfer (DET). Adverse events increase when moving from SET to SET+fzSET to DET. The probability of SET+fzSET being cost-effective decreases with age. When SET is included in the analysis, SET+fzSET no longer becomes a cost-effective option at any threshold value for all age groups studied.

CONCLUSIONS

The analyses show that the choice of embryo transfer strategy is a function of four factors: the age of the mother, the relevance of the SET option, the value placed on a live birth and the relative importance placed on adverse outcomes. For each patient group, the choice of strategy is a trade-off between the value placed on a live birth and cost.

Selective single blastocyst transfer reduces the multiple pregnancy rate and increases pregnancy rates: a pre- and postintervention study

Objective

To examine the clinical pregnancy rate (CPR) and multiple pregnancy rate (MPR) in a large in vitro fertilisation (IVF) programme before and after the introduction of single blastocyst transfer (SBT) strategy in a selected group of women.

Design

A 3-year pre- and postintervention study.

Setting

A tertiary reproductive medicine and assisted conception unit in a London teaching hospital.

Population

Two thousand four hundred and fifty-one fresh IVF cycles performed between July 2004 and June 2007 at the Assisted Conception Unit at Guy’s and St Thomas’ Hospital NHS Foundation Trust were included in the study.

Methods

In January 2006, we implemented a multidisciplinary intervention involving the introduction of a selective day 5 SBT service together with an educational programme on the risks of multiple pregnancy and potential advantages of blastocyst transfer aimed at couples at high risk of multiple pregnancy.

Main outcome measures

The CPR per cycle started and MPR per clinical pregnancy achieved.

Results

A statistically significant increase in the CPR from 27% (324/1198) to 32% (395/1253) (risk difference [RD] 5%, risk ratio [RR] 1.17, 95% CI 1.03–1.32, P = 0.015) and reduction in the MPR per clinical pregnancy from 32% (103/272) to 17% (69/395) (RD 15%, RR 0.46, 95% CI 0.35–0.60, P < 0.001) were observed after introduction of the SBT service.

Conclusion

Selective SBT in women with good prognosis can reduce the MPR after IVF while maintaining the overall success rate of the IVF programme.

Please cite this paper as:Khalaf Y, El-Toukhy T, Coomarasamy A, Kamal A, Bolton V, Braude P. Selective single blastocyst transfer reduces the multiple pregnancy rate and increases pregnancy rates: a pre- and postintervention study. BJOG 2008;115:385–390.

Safety versus success in elective single embryo transfer: women's preferences for outcomes of in vitro fertilisation

OBJECTIVE

To assess whether women waiting to undergo in vitro fertilisation (IVF) view adverse outcomes associated with twin pregnancy as more desirable than having no pregnancy at all.

DESIGN

Women's preference values for five adverse birth outcomes associated with twin pregnancy were compared with their preference value for treatment failure (TF), i.e. no pregnancy at all.

SETTING

Aberdeen Fertility Centre, University of Aberdeen, UK.

POPULATION

A total of 74 women waiting to undergo IVF.

METHODS

The standard gamble method was used to elicit women's preference values for giving birth to a child with physical impairments (PI), cognitive impairments (CI), or visual impairments (VI), perinatal death (PD) without a subsequent pregnancy, premature delivery (PremD), and TF (no pregnancy).

MAIN OUTCOME MEASURES

Preference values were elicited on a scale where 1 represents giving birth to a healthy child and 0 represents immediate death.

RESULTS

The median preference values for having a child with PI, CI, or VI were 0.940, 0.970, and 0.975, respectively. The median values for PremD, PD, and TF were 0.955, 0.725, and 0.815, respectively. Having no child at all was valued significantly lower than having a child with PI, CI, or VI (P < 0.01) but significantly higher than PD (P < 0.01).

CONCLUSIONS

Some women waiting for IVF treatment view severe child disability outcomes associated with double embryo transfer as being more desirable than having no child at all. Women embarking on IVF may be influenced more strongly by considerations of 'treatment success' rather than future risks to their offspring.