Women who are not yet ready to start a family may choose to freeze their eggs to keep the option on the table for longer.

There has been significant promise, but also significant disappointment, with egg freezing to date. The disappointment stems from the relative lack of success rate data. Many more women are freezing eggs than thawing them. And until they are thawed, how do we know how successful the treatment really was?

At first, the data was generally only coming from egg donors, women pre-selected to have eggs that would be expected to succeed. Significantly less data was available for “social” egg freezing, that is, women who are choosing to delay their reproduction and hope to be able to freeze their eggs in time. The majority of our patients were waiting for the latter data sets to come through, as we tried to keep expectations firmly in check.

We are now finally seeing the numbers, and it appears that for most patients egg freezing works as well as embryo freezing, with success rates often in the range of 60% (see this article for more). This published data fit our internal data suggesting clinical pregnancy rates 55-60% per set of eggs for women under 38.

Egg freezing is promising when we have enough good eggs to freeze. If you are under 38 years old (age being a marker for egg quality) and have been told you should be able to freeze 12-20 mature eggs (ie. you have a good ovarian reserve), and are working with a good lab able to offer vitrification, you may anticipate having three or more fertilized egg develop to blastocysts and a reasonable expectation for pregnancy in the future. No, it isn’t perfect – all things being equal frozen eggs do not work as well as fresh eggs – but with good counselling egg freezing may provide some measure of reassurance that had been missing until now.

For a good video that walks you through the process check out this video, or a more detailed scientific review, see this article.

The post New data on non-donor egg freezing success rates! appeared first on Fertility.ca.

Choosing the best embryo

The next day -day 1- each healthy embryo will still be a single cell, now at the two-Pro-Nucleii (2PN) stage. It is a black-or-white assessment, with little room for interpretation: either you have 2PN embryos, or you don’t. Most couples can expect 80-90% of the mature eggs to turn into 2PN embryos.

Embryos are rarely transferred at this point, because you really can’t tell which embryos of the group will be the most likely to continue to grow properly.

By day 2, the embryo should be 3-4 cells.

By day 3, the lab staff can finally grade the quality of the embryos by looking at them under a microscope. It is not a perfect science, but, it is our standard of care for the moment. The grading is done in two ways:

• We count cells. The ideal embryo has 8, 7, or 6 cells. More than this, and embryos may be growing too fast, using up the energy stored by the egg, and therefore more likely to burn out before they get the chance to implant. Slower than this, and the concern is that the embryos won’t continue to divide at all.
• As cells divide, they leave fragments behind…and too many fragments suggest that cells may not be dividing properly. We grade fragmentation on a 5 point scale, and ideally your embryos will be grade 1 or 2.

A perfect grading system would allow us to spot the ideal embryo every time. We’re working on that*, but in the meantime, to make up for our uncertainty, we usually encourage the transfer of more than one embryo.

For greater specificity in embryo selection , some doctors will encourage you to grow embryos along to day 5.

By day 5, listed in increasing order for pregnancy, we hope to see:

• morula
• cavitating morula
• blastocyst
• hatching blastocyst

A blastocyst will be about twice as likely to result in pregnancy as a morula.

Sometimes we will allow an embryo to grow to day 6 to become a blastocyst, but we won’t go further than that.

The pregnancy rate per blastocyst transferred is certainly higher than per day 3 embryo transferred, because the extra two days has allowed greater selection to occur. But in some ways, it isn’t a fair comparison. Perhaps pregnancy rates would have been just as good transferring 3 embryos on day 3 cf. 2 embryos on day 5.

In fact, doctors and laboratory staff will cite many factors when comparing day 3 to day 5, including patient age (some say >40y should always be day 3), optimization for freezing (historically better on day 3, but perhaps vitrification changes this equation), embryo health, the implantation window, uterine contractility…the debate goes on. Good people can disagree.

My advice would be to accept the day that your particular lab favours. In this way, you will be maximizing your chances as your work to the strengths of your particular group.

* Note that there are newer systems for embryo grading, include proteomics, metabolomics, and other variations in preimplantation genetic screening (PGS). I am happy to write to these topics, but they generally will not be offered in most laboratories in Canada or elsewhere.

The post IVF: choosing the best embryo, and the best day for embryo transfer appeared first on Fertility.ca.

We judge embryo quality in three ways: the number of embryos present, embryo grading, and PGS. In this post, we’ll talk about PGS.

Our current gold standard for judging embryo quality is pre-implantation genetic screening. PGS allows us screen embryos for genetic issues during an IVF fertility procedure. First, the embryo is extracted and fertilized in the lab. It’s given a few days to mature. Then the embryologist removes a few cells from the embryo and examines the chromosomes. Embryos with normal chromosomes are implanted in the woman’s uterus or frozen for implantation later.

The benefits of doing PGS are strong. For example, compared to an unscreened embryo, a single embryo screened with PGS typically:

• Implants more successfully

• Has higher delivery rates

• Reduces the risk of multiple pregnancies

• Reduces the risk of preterm delivery

For more on the science of PGS, you may want to visit www.chromosome-screening.org.

Note: Embryos are just one element in implantation. Implantation challenges can be related to embryos, the uterus and overall health. We’ll have another post shortly on how the uterus, its shape and lining, may impact odds for implantation.

The post What are the recent developments in implantation? (Part Three: PGS) appeared first on Fertility.ca.

Embryo grading means we look at embryos under a microscope and estimate whether they have the potential to continue to grow into a healthy, ongoing pregnancy. Grading is done by removing embryos from the incubator for a few seconds (up to a minute) every day, or nearly every day, for the first three to five days prior to embryo transfer. This gives us about two minutes worth of data acquisition over the ninety-six hours it could take to grow an embryo into a blastocyst.

But it’s an inexact science at best. The embryos are only a few days old. There’s a lot of development that happens over nine months.

Recently, we have been using cameras that follow embryo development 24/7. It sounds better, and in some ways it is. It’s an extraordinary amount of information to have. One of the current challenges is what to do with it all.

All kinds of patterns have been observed, but their clinical significance, at this time, remains unclear. If an embryo is not growing as well as expected, does that mean it should never be transferred? Often, we don’t know.

In the months ahead, I’ll be able to share more information with you as we collect more data.

The post What does embryo grading really mean for my chances of having a baby? appeared first on Fertility.ca.