SpainFertility

Discussing the effect of FSH levels and age on the risk for aneuploid embryos in women undergoing IVF.
Age significantly alters the risk for aneuploid embryos in women undergoing IVF, while levels of follicle stimulating hormones (FSH) have no effect on the risk for this outcome, scientists in the UK claim.

“There is an ongoing debate regarding the etiology of the reduction of fecundity for women who have elevated basal FSH and regarding whether this etiology is associated either with poorer oocyte quality or lower ovarian reserve,” explain Meen-Yau Thum (Lister Hospital, London) and co-workers.

To settle this debate, Thum and team studied 151 women aged an average of 40 years, who were undergoing IVF.

They found that the risk for aneuploidy was around 50.0 percent in the 32 women with basal FSH levels of 10 IU/l or over and a comparable 50.2 percent in those women with basal FSH levels of below 10 IU/l.

In contrast, age significantly predicted the risk for aneuploidy, which occurred in 56.2 percent of women aged 38 years or over and 37.5 percent of those younger than 38 years of age. Of note, the link between age and aneuploidy risk was independent of FSH concentrations.

Based on these results, the authors reason that “a delay in treating women with elevated basal FSH is counterproductive, because the oocyte number and genetic quality will deteriorate as maternal age increases.”

Evidence reflecting the success of human oocyte freezing with the technique of vitrification is now so strong that its use in fertility preservation should be reconsidered, according to a proposal in the journal Fertility and Sterility.

Three senior figures in the field write: “The reported success of the use    of this method [vitrification] should stimulate a renewed debate on oocyte storage for fertility preservation without a medical indication.”

The cryopreservation of oocytes has long been a challenge in reproductive medicine, but its success has been elusive and frustrating. Indeed, 2 years ago, at the 2006 annual meeting of ESHRE (European Society of Human Reproduction and Embryology) in Prague, Dr Masa Kuwayama from Tokyo estimated that no more than 150 babies had been born worldwide following oocyte cryopreservation by conventional “slow-freeze” methods.

But the vitrification method he described, which requires the very rapid freezing of cells (to -196oC) in very small volumes of solution, prevents the formation of ice crystals and thereby damage to the oocyte after thawing. Intra-cellular crystallization was believed to be the main cause of damage to the oocyte’s meiotic spindle and chromosome alignment. Vitrification, said Dr Kuwayama, preserves the oocyte in a glass-like state without crystallization, paving the way for a cryopreservation method as effective for female gametes as for male gametes. Results presented in Prague showed that 94.5 percent of 111 cryopreserved oocytes survived thawing, 90.5 percent were fertilized by intracytoplasmic sperm injection (ICSI), and 50% percent of the resulting embryos cleaved sufficiently for transfer. Twelve pregnancies were recorded from 29 transfers, a pregnancy rate of 41.9 percent.

In the short time since that meeting, vitrification has been widely adopted, particularly in countries like Italy and Germany where embryo freezing is banned by law. One recent randomized trial from Valencia found no difference in reproductive potential (survival, fertilization, and cleavage) between fresh and vitrified oocytes in a series of egg donors whose oocytes were randomly assigned to undergo fresh fertilization or fertilization following vitrification and warming an hour later.[2] The authors of this report noted as a result that vitrification of oocytes has “a high potential for establishing oocyte banking.”

Many other studies over recent months have reported similar results, with pregnancy outcomes in vitrified oocytes comparable to those from fresh cycles. Indeed, one group—from Lubeck, Germany—after describing their results for the freezing of zygotes by vitrification, asked: “Is it still fair to advocate slow-rate freezing?”

Such results, however, are in small groups of patients, and rarely in well-controlled trials. Thus, in a recent review of oocyte cryopreservation, one of its research pioneers, Dr Debra Gook from Melbourne, proposed that “the small number of babies born from clinical oocyte cryopreservation and the paucity of well-controlled studies currently preclude valid comparisons between approaches.”[3]

This latest review from three respected figures in IVF suggests that the results now achieved with vitrification are indeed sufficiently robust to at least reconsider fertility preservation as an indication for oocyte freezing.

So far, the indications for oocyte freezing have been only medical—in advance of radio- or chemotherapy, and other conditions of premature menopause. But now, in the face of lower fertility rates and delayed maternal age among women in all developed countries, the authors propose that “the successful preservation of oocytes by vitrification will provide the ‘aging’ woman who has had to delay her childbirth, for any reason, the opportunity to conceive and deliver using her own oocytes at the time she decides.” This is a hot issue in reproductive medicine, and one which, for the first time, may extend treatment from a medical to a social indication.

Orgyn.com

Canadian obstetrics and fertility societies publish joint guidance concerning the number of embryos that should be transferred following IVF.
The Society of Obstetricians and Gynecologists of Canada and the Canadian Fertility and Andrology Society have published joint guidelines for the number of embryos to transfer following IVF.

The guidelines extrapolate from a review of English-language articles listed in the Cochrane Library and MEDLINE from 1990 to April 2006, along with references identified from the bibliographies of the primary articles.

The collaborators write: “This guideline is intended to minimize the occurrence of multifetal gestation, particularly high-order multiples, while maintaining acceptable overall pregnancy and live birth rates following IVF-embryo transfer.”

Among the 13 recommendations, the guidelines state that individual programs should look at their own data to identify determinants of implantation and live birth rates and develop their optimal embryo transfer policies.

In general, fewer blastocyst-stage than cleavage-stage embryos should be transferred, particularly in women with both “excellent” prognoses and high-quality embryos, the guidelines state.

The authors explain: “Women with excellent prognoses include those undergoing their first or second IVF-ET cycle or one immediately following a successful IVF-ET cycle, with at least two high-quality embryos available for transfer.”

The collaborators say no more than two fresh embryos should be transferred in women under 35 years of age, and those with “excellent prognoses” are candidates for single embryo transfer.

No more than three embryos should be transferred in women aged 38-29 years, and no more than four in patients over 39 years of age.

Comparing the merits of a novel electrophoretic sperm sorting system and conventional density gradient sperm centrifugation in assisted reproduction programs.
An assisted reproduction tool designed to sort sperm according to quality is no more effective than standard selection by centrifugation, but may save time, findings from a prospective controlled trial indicate.

Sperm to be used in assisted reproduction techniques are usually separated from seminal fluid by discontinuous density gradient centrifugation (DGC). However, Steven Fleming (Westmead Hospital, Sydney, Australia) and colleagues note that the technique does not sort sperm for quality, unlike a recently developed electrophoretic filtration system that can separate sperm according to extent of DNA damage.

To test the value of the electrophoretic system, the researchers separated semen samples from 28 couples undergoing IVF for preparation by both conventional DGC and electrophoretic filtration.

The authors report that sperm recovery, motility, and DNA fragmentation were similar in sperm isolated using the two techniques.

Electrophoretic filtration and DGC also led to similar rates of fertilization (62.4 and 63.6 percent, respectively), cleavage (99.0 percent vs 88.5 percent), and numbers of high quality embryos (27.4 percent vs 26.1 percent).

“Membrane-based electrophoresis is an efficient and reliable means of sperm preparation that is as effective as DGC,” summarize Fleming et al.

“It is also an intrinsically faster and simpler method of sperm preparation, involving a shorter learning curve,” the researchers add.