I think my comments have been misinterpreted as a brief for abortion, or as based on the assumption that no one cares about “miscarriages.”
In fact, I consider myself basically a pro-lifer, and of course “miscarriages,” as the term is typically used (Merriam-Webster says it applies “especially between the 12th and 28th weeks”), can greatly scar a mother and should be treated as a loss of human life. That’s why it’s a good thing to work at reducing them and why we invest so much in that project. The belief that underlies this opinion, at least for me — the belief that by the time fetal development reaches the point where a woman might say she “miscarried,” the baby she is carrying is a human life — is why I support most anti-abortion efforts. (Others might support anti-miscarriage efforts simply to help women have children, even if they think the fetus saved isn’t a human life, of course.)
To me, this is consistent: It treats certain fetuses as human lives both for the purpose of legal protection, and for the purpose of life-saving efforts in the face of natural death.
However, as Yuval notes, most miscarriages (more broadly defined) occur at a very early stage of development (even if the number Ron Bailey cited is inflated). If we see the embryos lost this way as human lives, too, this is catastrophic — countless human beings dead — and we should try to stop it, not merely forbid people to destroy even more embryos intentionally. One way to do this would be to develop drugs that women attempting to become pregnant could take to reduce the chance that their body will naturally destroy an embryo before they realize it’s even there. (Existing fertility drugs might even act this way; I’m not sure.)
It seems to me that if you truly believe that embryos are human lives, you would support investment in these drugs proportional to the lives that could be saved and the chance that the drugs could be successful, would believe that women have a moral obligation to take such drugs before having unprotected sex, and might even think that some level of government should require and pay for them. I see nothing wrong with actually believing these things — I just think they follow from a belief that destroying very early embryos is the taking of a human life, and I doubt most opponents of embryonic stem-cell research would sign on to them.