Big Decision Time

All systems are go for the embryo transfer this week, and we’re pretty thrilled with how well things are going so far. But we’re faced with a big decision.

We have five lovely day 3 (8-cell) embryos on ice. Four look near-perfect and one is a bit behind on growth. But I’ve heard plenty of stories of the runt turning into a beautiful healthy baby. Sometimes it turns out to be the only viable embryo!

Embryo development, day 1 – day 5

So here’s what we’ll have to decide:

(a) Thaw the two best-looking embryos and immediately transfer them (day 3 transfer), or

(b) Thaw ALL FIVE embryos, see which one(s) develop in the lab to day 5 (blastocyst stage, with about 100 cells), transfer the two best-looking ones (if two even survive), and freeze any leftover blastocysts again (if more than two survive).

Here are the benefits of the day 3 transfer:

• The embryos aren’t in the lab as long — they’re back in vivo where they belong. Studies have shown that there’s no benefit to taking a specific embryo to day 5 vs. day 3. Meanwhile, I’ve heard bone-chilling stories of human errors in even the best labs in the world. While they are very rare, that doesn’t mean much if it happens to you. And since we’re talking about so few embryos, and everything it took to get them, a pretty extreme level of conservatism seems justified.

• There’s conflicting evidence whether, even in the best lab settings, taking a group of embryos to day 5 provides much benefit. If you have fifteen embryos and want more data about them before choosing which one(s) to implant (especially if you only want one or two kids), taking them all to blast probably makes sense. You’ll end up with maybe six or seven blastocysts, and implanting two at a time, you’ll have a great chance to get pregnant quicker than implanting two “untested” day 3 embryos at a time, and without implanting three or four and risking triplets or more. But if you only have five embryos, you’re taking a much bigger risk, and losing even one potentially viable embryo is pretty tough to swallow.

• If we do a day 3 transfer with two embryos, and keep the other three on ice, we’re guaranteed at least one more shot at parenthood if this transfer doesn’t work. If we put all five eggs in one basket, there’s a chance that not only will we have only one shot at a transfer — we may end up with zero. I’ve heard more than one story of a couple excitedly getting ready for a day 5 transfer only to be called on the morning of and told the embryos had all “arrested” (died) overnight. It’s possible they might have died anyway, and dying in the dish saved the couple the pain of a miscarriage. But as for me, I’d always wonder if one of them might not have survived if we’d done an earlier transfer.

• If we did a day 5 transfer and were lucky enough to have more than two survive to blastocyst, we’d have to re-freeze any extras. Personally, I’d rather not subject the embryos to any more intervention than absolutely necessary. More than 95% of embryos tend to survive freezes and thaws these days, but each intervention adds more possibility for bad luck. Seems safer to just leave three in the cryo tank, either for another try for #1, or for a sibling down the road.

• At least back in 2003, the sex ratio (male/female) for blastocysts was approximately 1.3, while the ratio was much closer to 1.0 for day 3 embryos. Which means, apparently, that lots of perfectly good female embryos were falling by the wayside on the way to day 5. Lest you accuse women of being finicky even in vitro, the egg controls growth and development until day 3. That’s when the sperm’s genetic contribution starts kicking in. Apparently there’s something about X sperms (as supposed to Y sperms) that isn’t so crazy about dish life. Of course, I’m not a trained professional, so there may be a totally different explanation. This is just mildly educated conjecture. And a lot of things have changed since 2003, so the sex ratios may be different now. But if those stats hold up, I’d hate to lose any potential daughters to the petri dish patriarchy. 😛

It’s raining day 3 embryos…

• I’d rather risk a miscarriage, and risk having to come back to Istanbul to do another (relatively easy) frozen embryo transfer, than risk having either zero or only one shot with these embryos, and I’d certainly prefer it to another IVF cycle.

• I would probably choose to implant two whether it’s with day 3 or day 5 embryos, so if I go with two day 3 embryos, there’s probably less of a chance for twins. Overall I’ll be grateful for any pregnancy, but if I had my choice, I’d rather not take the (significant) risks of a twin pregnancy with my first.

• It’s anecdotal, but I’ve heard several stories of women who were advised to go ahead and implant their embryos on day 3 because it was clear they would never make it to day 5 in the lab. In many cases, those “failing” embryos turned into healthy kids.

• Emotionally speaking, thawing all five at once and waiting for phone calls each day about how many had survived would turn me into a nervous wreck just when I need to be in a positive energy state to welcome a new being into my own.

Hatching blastocyst. It isn’t ours, but isn’t it pretty? Like a galaxy being born.

Here are the benefits of the day 5 transfer:

• Many doctors argue that only the non-viable embryos die on the way to day 5, so there’s really no loss, and you end up with much more concentrated quality in the group that survives to day 5. It seems true that you do end up with a higher percentage of quality embryos. But no one is really sure if perfectly good embryos might die in the lab that could have survived in the body, and with only five embryos, “percentages” don’t mean a whole lot.

• Of course, a day 5 blastocyst can still be chromosomally abnormal and thus non-viable (roughly half will be abnormal on average for any given couple), but the chances are less. So you can more confidently place only a single embryo and not risk twins (or only two and not risk triplets) — though with day 5 embryos, there is a slightly elevated risk of a blast dividing into identical twins (which carry even more risks than fraternal twins).

• It can potentially save me from wasting my time with two dud embryos and save me an extra trip to Istanbul.

• The doctor says our embryos look great, so it’s very unlikely they’ll all die before day 5. But we’re not a “representative sample.” We’re one couple. “Unlikely” won’t mean much to us if we’re in that unlucky category.

So I guess I’ve already made up my mind (after hours and hours of research, reversals, and soul-searching). But part of me wonders if I’m being too conservative — if I shouldn’t trust the lab techs and the experts and save time and money by gathering that extra data about what we have and choosing (hopefully) the best and just doing this once.

A big part of it, I think, is regret management. If I have to make an extra trip to Istanbul and things still don’t work out (or if they do!), I can know I did everything I could and didn’t take any unnecesssary risks. If we take the “easier” route and things go wrong, I think I’d feel a lot worse about that.

If all this embryo talk bores you to tears, by all means, go read something else. 🙂

For the rest — particularly if you’ve had any experience in this arena — I’d be glad to hear your thoughts.

UPDATE: If you read the next post, you’ll know (though you probably could have guessed!) that we went with the safer day 3 transfer, and we still have three embryos in cryo tanks. I feel good and confident that we made the best decision for us. Inshallah!