IVF Research at The Fertility Center of Las Vegas (FCLV)
Our research has resulted in numerous publications, honors, and awards, and has been presented in seven countries. More importantly, it allows us to improve our methods so that we attain some of the best IVF success rates in the United States, helping more couples to realize their dream of bringing home a healthy baby.
Some studies can offer free or discounted cycles to participants, free medications, or may access advanced technologies before the general public.How Our Research Improved Our IVF Success Rates
Years ago, we noticed greater success rates with thawed embryos than with fresh embryos. This made us suspect the uterus was more receptive in the absence of ovarian stimulation.
Further investigation found that slower (day 6) blastocysts had reduced success in fresh non-donor cycles, but not in frozen embryo cycles, nor in egg donor cycles. Other scientists had reported that endometrial development was advanced by ovarian stimulation. We surmised that ovarian stimulation was advancing the “implantation window” so that the fastest embryos tended to implant, while the slowest embryos (day 6 blastocysts) often missed the window. This effect vanished in cycles where the recipient was not stimulated.
Since we published that result, other researchers have verified our findings, and other centers have followed our lead by electively freezing day 6 blastocysts. Our further research found the day the embryo forms a blastocyst remains important is one important factor in the synchrony between the embryo and endometrium.
We did not stop there. Our thawed blastocysts were implanting more often than our fresh blastocysts, but not as often as fresh blastocysts in our donor cycles. Why not? They were going into a similarly prepared uterine environment. We suspected the “surviving” thawed blastocysts had damage that prevented some of them from resuming development and implanting.
We therefore decided on a different approach. We tried freezing all the embryos at an earlier stage, and cultured them to blastocyst after thaw. This way, we had 4-5 days after thaw to confirm that the blastocysts resumed normal development. We called this method “post-thaw extended culture” (PTEC).
We found that PTEC blastocysts had implantation and pregnancy rates similar to our fresh egg donor cycles. The PTEC blastocyst placed into an ideal environment results in some of the highest implantation and pregnancy rates in IVF.
We then compared PTEC transfers to fresh blastocyst transfers in randomized trials. We found PTEC yielded greater implantation and pregnancy rates than fresh transfers in normal responders. This supported the hypothesis that endometrial receptivity is impaired by ovarian stimulation.Healthier Mothers and Healthier Babies
A drug called hCG is commonly used to mature the eggs following ovarian stimulation in almost all IVF cycles around the world. This use of hCG has been associated with a potentially serious condition called ovarian hyperstimulation syndrome (OHSS).
We studied the relationship between hCG and the incidence of OHSS. We controlled the risk of OHSS by reducing hCG dose in high-risk patients. In 2004, we began using a different drug (GnRH agonist) in high-risk patients. This eliminates OHSS in those patients and allows us to stimulate them optimally without significant OHSS risk.
We also developed and published an innovative “dual trigger” using GnRH agonist combined with a small dose of hCG in patients with intermediate OHSS risk. Many other clinics have started using this “dual trigger”, again following our lead.
Among the greatest risks to IVF patients and their babies is the risk of multiple pregnancy, especially high order multiple pregnancy (triplets or greater). The best way to reduce this risk is to transfer fewer embryos. FCLV was among the first centers in the United States to transfer no more than two embryos per transfer, on average, in every age group and in every type of cycle, including fresh transfers, frozen embryo transfers, and donor egg cycles.
Of course, any clinic can transfer fewer embryos. But the transfer of fewer embryos is only practical with high implantation rates, or else success rates will suffer badly. FCLV has implantation rates well above the national averages. In 2009, our implantation rate in patients <35 years old was 53.8%, while the national average was 35.6%. That’s why we could transfer just 1.8 embryos, on average, and still achieve a live birth rate of 58.5% per transfer (the national averages were 2.1 embryos and 47.5% live birth in that age group).
Reducing the Risk of Ectopic Pregnancy
An ectopic pregnancy occurs when an embryo implants outside the uterus. Our research has revealed that our frozen embryo transfers have lower risk of ectopic pregnancy when compared to fresh transfers. It appears that ovarian stimulation may affect the uterus in various ways that might increase the risk of ectopic pregnancy. This might explain why other researchers have found elevated ectopic pregnancy rates with fresh transfer. Our frozen embryo transfers avoid this problem, and we have found reduced ectopic pregnancy rates with our frozen embryo transfers. Fresh donor cycles also avoid the problem because the recipient is not stimulated, and our donor cycles have very low incidence of ectopic pregnancy.
Many researchers have found that the infants from fresh embryo transfers were more likely to have low birthweight than those from frozen embryos. Subsequent research, including ours and others, revealed this effect is not due to embryo freezing. It seems the current best explanation is that the uterine environment is compromised by stimulation, not only making implantation less likely, but also impairing embryo growth when implantation does occur in fresh cycles following stimulation. Embryos attach to the uterus a little better if there has been no ovarian stimulation in that cycle.
At FCLV, we often recommend transfer of frozen embryos instead of fresh. Healthier babies may be one more benefit of this practice.Egg Freezing and Fertility Preservation
FCLV has been freezing eggs since 2004, in one of the longest-running and most experienced oocyte freezing programs in the United States. We also realized our first live births from frozen eggs in 2004, and many more since then.
ASRM guidance recommends that any egg freezing should be done under a research protocol with independent ethical oversight. The egg-freezing program at FCLV is set up exactly that way.Earlier Pregnancy Monitoring
Most centers measure hCG 10-14 days after embryo transfer. We routinely measure hCG earlier than that. We showed that just 5 days after embryo transfer, we usually tell the outcome of an IVF cycle, and we can notify most patients of their pregnancies. Of course, some embryos implant later than that, and we perform additional later tests (day 7 and day 10) to watch for those. But most implant by day 5, and our patients appreciate early notification of their pregnancy.