FREEZE! don't move....

that's what embryos 2, 3, 4, 5 and 6 are doing.....freezing!
 If you recall, #7 stopped dividing and #1 went on to the next step 

So after harvesting my mature eggs as a result of grueling hormone therapy with ovulation-inducing drugs, the last thing I wanted to do was let them go to waste.   The goal is to not to have to start over with stimulation of ovaries with injectable medications if we needed to repeat the IVF process.  That's why it was crucial, as painful as it was, to adhere to dosage instructions and injection times (down to the minute)...to give my body the best chance at producing as many mature follicles as possible for a one-time harvest.  It worked!  We ended up with enough remainders for cryopreservation (freezing).  The need for multiple harvests is not only taxing on one's body (and marriage) but can be very expensive, especially since most insurance plans max at 2-3 harvests a lifetime.

Cryopreservation, in this case, is the process of freezing embryos in sub-zero temperatures, which preserves the integrity of the eggs at the division stage and allows them to be thawed at a later time to continue dividing/growing.  It's an advancement in science that has greatly improved the IVF process, in that embryologist can select the highest quality eggs to fertilize, knowing they can be stored for later use.  It also no longer pressures doctors and couples to transfer multiple 'good eggs' into the patient for fear of losing them.  When that used to be the case, couples would end up with multiple births...triplets, quadruplets, quintuplets, etc.  So the solution to infertility was....you either had 'no children' or seven, eight, nine you could barely afford to raise.  Too many extremes.

Sometimes, the first embryo transfer doesn't end up in a pregnancy, or does but ends in a miscarriage.  In this case, there'd be 5 more chances for embryo transfers and increased rate of a birth.  The cryopreserved embryos can be stored for years and thawed for use when needed.  The process is usually not covered by insurance, so it's an out of pocket expense to consider but generally inexpensive -- between $500 - $2000 per year depending on number of embryos.

There's a catch though with cryo.  Unless you're a cancer patient opting to cryopreserve your (unfertilized) eggs before chemotherapy, there are strict rules that govern the freezing of fertilized eggs.  In our institution (and I imagine everywhere else), I had to be with a committed male partner (whose sperm I was using) and he had to express written consent of his desire to have biological children with me in the future.  Of course the consent form was 17,000 pages long, it seemed, and we had to sign off on our desired actions for the frozen embryos should a number of unforeseen life events happen (i.e. divorce, death of patient, death of partner, separation, death of both, change of heart).  In each scenario, I had to decide if I'd discard my eggs, donate to an infertile couple, transfer to ex-husband and his new wife (HAAAA!!!!!)!

no seriously.....HAAAAAAAAAA!!!!!!!!!