Couldn't the objection to IVF just be that often it results in more embryos than will be implanted and those embryos will likely be discarded? Isn't that the most common religious objection to the practice?
While the I think the whole case is very sad and I'm glad the last 4 babies are not going to die, I just don't see why it is particularly hypocritical for Jehovah's Witnesses to allow one type of medical intervention and not allow another. Many other religions make similar distinctions. As far as I understand, according to the Catholic Church (I'm just using them as an example because I was raised Catholic and its easy to find info on Catholic doctrine) it's okay to take a pill in order to get pregnant, but not in order to prevent pregnancy. And it's okay to have surgery to remove scar tissue from fallopian tubes to help with pregnancy, but it's not okay to undergo IVF. I'm guessing other Christian sects also have similar beliefs. Of course, one could call hypocrisy for all of these things because they're all medical interventions which don't leave things up to God's will, but I think the response would be that the determination of whether or not these things are okay is not a matter of the fact that they are medical interventions. I believe for the Catholic Church it is a matter of whether the procedure assists or replaces the act of sex between husband and wife. With regard to Jehovah's Witnesses, as far as I understand, the objection to blood transfusions is very specifically an issue about blood--not about letting nature take its course or allowing God's will to be done. IVF or fertility drugs are not about blood. So I don't see that they are any more hypocritical then, say, the Catholic Church.
Now of course, if you want to go deep into you might think it is hypocritical to pull out certain lines of the Bible (ones that mention blood) and give them special significance over others. Hey, I'm totally onboard with this criticism. But this criticism extends way beyond Jehovah's Witnesses and seems that it will apply to most versions of Christianity (and likely most other scripture based religions).
So the difference between this case and any other religious beliefs can't be hypocrisy, but rather just that this case is a life or death situation whereas most of the time members of other religions following their beliefs is not so clearly a matter of life or death (at least not in developed nations; of course, lack of access to birth control results in tons of death of women and fetuses in developing countries where pregnancy is much riskier for the average woman than in the U.S. or Canada).