Are We Doing Leftovers Tonight…What’s in the Freezer?

Nothing tastes better the day after, the week after, or certainly after it’s been sitting in the freezer for a while (except maybe Haagen Dazs coffee ice cream!). With this being said (and true), it’s hard to believe that frozen embryos are as good as, if not better, than fresh embryos. Explaining this to patients can be incredibly confusing—and rightfully so. Who wouldn’t think that fresh chicken is better than the stuff you defrosted last night?

Given our perception of food and what happens after a stint in the fridge or freezer, it can take a while to convince patients to take a pass on the fresh embryo transfer and opt for a frozen one. However, embryo freezing has come “a long way, baby” since the first baby was born in Australia in 1984. Currently, nearly half of IVF transfers in this country are frozen embryo transfers. So why the shift? Changes in the freezing process and techniques have resulted in frozen embryo transfer success rates that in some cases top those of fresh cycles. Data from our OB friends have shown that babies born after frozen cycles do better in utero and as infants than babies born after fresh cycles! Large studies have shown lower rates of preterm delivery, low birth weight, growth restriction, and mortality after frozen embryo transfers—pretty impressive stuff.

Furthermore, the congenital anomalies/malformations that arise after frozen embryo transfers are no different than after fresh transfers. Your next question is likely…why? What could possibly be better about something that was frozen and then thawed rather than something that was hot (or fresh) off the press? Here’s the deal.

Researchers believe that it has something to do with the uterus and the endometrium’s ability to receive the embryo after a fresh vs. a frozen embryo transfer. The thought is that maybe the high estrogen levels seen in many fresh IVF cycles, while beneficial to the ovaries, may be detrimental to the uterus. An “unhappy uterus” means “unlikely to have implantation.” And if you take it one step further, maybe the high estrogen levels not only decrease the chance of implantation but also the ability of a good placenta to form.

Poor placental development will ultimately translate into poor fetal growth (hence, the higher incidence of growth restriction and low birth weight after fresh embryo transfer cycles). Whatever it is, the data are fairly impressive. And while we are all rah-rah-go frozen embryo transfers for the above reasons, there are also two more important reasons to raise the pom-poms:

1. When embryos are not transferred back into the uterus during the fresh cycle, it gives your body a chance to go back to baseline. Deep breath in, deep breath out! The pause allows your body and, in many ways, your mind to reset. Without a pregnancy in the uterus to provide the juice to keep the ovaries revved up and enlarged, you will get a period about 7–14 days after the retrieval. And this breather is more than just getting your pants to button again (although it does feel good!). It allows your body to return to baseline and prepare for pregnancy with a more normal hormonal environment.Additionally, for those of us who are exercise fanatics, once you get a period you can resume your normal activities (#run #spin #yoga). While we know that exercise is not the most important thing in the world, it and any activity you do to keep you sane are pretty important. If we can help you maintain some normalcy in the midst of shots, vaginal ultrasounds, and never-ending blood draws, we most certainly want to do that.
2. Recently, embryo freezing has taken on a whole new meaning; it now is a major player in the genetic testing of embryos game. Call it what you want: PGS, CCS, TE biopsy. Embryo testing has become all the rage. It provides patients with important information, significantly increases success rates, and majorly reduces the twin rate. It’s the triple threat! However, in order to get an accurate read on all of your embryo’s genetic material it takes time. In a fresh embryo transfer cycle, time is of the essence. But if you freeze the embryos, time is also frozen. With the embryos on ice, you have time for chromosomes to be checked and your chances increased.

Bottom line, fertility treatment can be a cold place if you don’t have up-to-date information on what’s going on in the field of reproductive medicine. Be fluid; don’t be “frozen” in your thinking patterns or your plans. Medicine changes faster than ice melts in the summer. Ask your fertility doctor about what’s hot and what’s cold. You might be surprised at what’s hiding behind the frost!