LITERATURE for the INFERTILITY CLINIC
In this section, we offer commentaries on a broad survey of recent articles in the English literature. Articles are mostly chosen for two reasons: their potential translational value for immediate clinical practice or to help in determining where clinical practice might evolve to.
Mixing embryos for transfer
Here is an interesting paper in RBMOnline (1). Chinese investigators in a retrospective cohort study of Chinese numbers (n=11,738) of women, investigated what happens if only 1 good blastocyst is transferred or this good blastocyst gets for the transfer a poor-quality second blast as co-traveler. And the results were not surprising but still quite remarkable: Two embryos did better than one embryo, as the live birth rate was higher with good/poor embryo double transfer than with only one single good blast. Moreover, this higher pregnancy rate was also associated with a higher twinning rate (41,4% vs. 1.8%).
There are two important lesson to learn from this paper: (i) As already noted, two embryos are always better than only 1 in establishing pregnancies and achieving deliveries. (ii) But there is also a second important lesson: while we don’t know how good or bad our Chinese colleagues were in evaluating the quality of their embryos (especially considering the very high twinning numbers), one must wonder whether they did not underrate their embryos by morphology. The ultimate lesson, however, is an old one: even pretty ugly embryos at times still give you perfectly fine pregnancies and deliveries. So, don’t be too generous in discarding embryos!
And here is a second paper in which embryos were mixed up on purpose. Here the question was whether there was a difference in outcome after a fresh two-embryo transfer on day 3 or a fresh single day-3 embryo plus a subsequent frozen-thawed blast. And the answer was, in women under age 38 the combination of one fresh day-3 and one frozen-thawed blast produced a higher live birth rate and lowered the twinning rate in comparison to two fresh day-3 embryos being transferred (2).
To be honest, we have our doubts about this paper. Even the authors acknowledge some quite important limitation to their data. So, we would not put too much onto this manuscript’s conclusions; but it certainly attempted to address an interesting question.
References:
1. He et al., Reprod Biomed Online 2024;49(3):104104
2. Wanh et al., Hum Reprod 2024;39912):2702-2710
The interaction between female and male age in regard to IVF cycle outcomes
Everybody, of course, knows that female age represents the single likely most crucial factor in determining IVF cycle outcomes and male age plays comparatively only a very limited role. How both partners ages interact, however, had not been investigated until recently, when UK investigators tried. What they found was indeed quite interesting: In fresh IVF cycles, male age mattered more than one might have expected starting at age 40 if the female was between 36 and 39 years old but did not matter at all if the female was under age 35 or over age 40 (1).
The authors of the paper failed to explain these findings, and we must acknowledge that we also thought hard about how these female age-dependent differences could be potentially explained without coming up with a potential explanation. The only possible explanation that comes to mind is that at both female age extremes—very young and older—IVF cycle outcomes are poorer than in-between these two extremes. Maybe the male at these extremes does not matter as much anymore because egg issues prevail. But since finding even a workable hypothesis for the age-related findings in this study are difficult, a degree of skepticism regarding this paper appears warranted.
The authors must be given credit for, themselves, offering a substantial list of shortcomings of their study, which likely—combined—must be considered responsible for an “accidental” and, therefore, likely irrelevant finding. The likely conclusion, therefore, must be that our understanding of effects of female and male age on IVF cycle outcomes has not changed much as a consequence of this study.
Reference
1. Datta et al., Hum Reprod 2024;39(1):2491-2500
Egg and embryo donation
In the journal’s Fertility Battle series Fertility and Sterility recently addressed the question of whether egg sharing is ethical, with two proponents and three opponents contributing to the discussion (1). Considering the explosive growth the donor egg bank industry has been experiencing, to us this question has become mute. Isn’t what frozen egg banks do, egg sharing?
Diane Tober, an associate professor of Anthropology at the University of Alabama and the Institute for Social Science Research, just published a 2025 edition of her Google Book “Eggonomics” (see figure below), which offers an interesting and, at times, controversial perspective on egg donation (2).
The Reproductive Times would welcome a review of the book, if anybody is interested in writing one (up to 500 words) (2).
Also worth mentioning here was the second oral presentation at the 2024 ASRM meeting in Denver (2), in which Sarah Holley, PhD, a psychologist at the University of California, San Francisco, presented very interesting data on how egg donors apparently feel after donations (3).
The abstract summarized the study as follows: The average age of the studied donors was 34.9 years old (range: 24 – 47 years). Participants had donated an average of 2.8 times (range: 1 – 8). A large majority (88.3%) felt positively (i.e., proud, good, happy) about having been a donor. Most (58.3%) were not concerned about their health or future fertility, though a minority (23.6%) voiced concerns. Most donors (73.6%) were curious about the child(ren) born from the donation, though only 10.3% reported thinking repeatedly about the experience or the potential children from their donations. Interestingly, about half (46.8%) expressed a desire to someday meet the child(ren), while two thirds expressed willingness to meet if requested. Regarding release of their identity to a child (age 18 or over) upon request, 62.2% expressed willingness to have their identity disclosed and an additional 21.7% expressed uncertainty; only 16.1% reported they would not be willing to have their identity disclosed (4).
And finally, the practice committees of ASRM and SART published an updated opinion guidance document on gamete and embryo donation.4 Always worth the read!
References
1. Shah et al., Fert Steril 2024;122(6):984-990
3. Holley et al., Fertil Steril 2024; DOI: 10.1016/j.fertnstert.2024.07.072. Abstract O-2
4. Practice Committees of ASRM and SART. Fertil Steril 2024;122:5(:799-820