Spontaneous abortion

I've noticed some people arguing the fact that a woman's body "naturally rejects hundreds of fertilized eggs in her lifetime" (source) is meant to imply pro-life proponents are inconsistent in defending life at conception. This, in turn, is meant to imply abortion is morally licit.

On the one hand, most pro-life proponents believe life begins at conception. But on the other hand, if so, then why do pro-lifers not mourn the loss of these "hundreds of fertilized eggs"?

I'd like to make some preliminary notes on the topic, and perhaps come back to more specific details at a later date if I can find the time:

1. There are issues with language use.

   a. What precisely is meant by "naturally rejects"? Also, the term "rejects" is much stronger than a term like, say, "loses." Not only do people who speak like this need to be more specific in what they mean, but they also need to make a case for the stronger terminology. Does this accurately reflect what occurs in a woman's body?

   b. Plus, why use terms like "fertilized egg" which seem at the outset to imply a less than human entity? Is this intentional?

   c. Likewise, what about the use of "spontaneous abortion" as a term in lieu of, say, miscarriage? Is this an attempt to co-opt language in the culture wars? (Such as described in George Orwell's essay, "Politics and the English Language.")

2. There are issues with the accuracy of spontaneous abortion rate statistics.

   On what basis does the estimate that "hundreds of fertilized eggs" are "reject[ed]" rest? Do medical scientific or epidemiological studies form the foundation for this statistic?

   Now, I haven't looked at most of the medical scientific studies on which such an estimation would be based. I've seen a few, but not all.

   I've seen others cite similar statistics. In fact, I've seen others cite estimates as high as 50%. But for most people I can't tell from where they're getting their numbers.

   This makes wonder what people are basing their stats on. Is most of it second or thirdhand information? Pro-abortionist bloggers citing ignorant pro-abortionist bloggers who heard it from still other ignorant pro-abortionist bloggers and so on?

   Are there reliable stats for spontaneous abortions?

3. There are issues with medical scientific, epidemiological, and related studies.

   a. That is, it's not merely about reading the medical scientific studies. It's about making sure the medical scientific studies themselves are reliable and representative and so forth. Just because a study is published in a prestigious scientific journal doesn't necessarily mean it's a valid or sound or otherwise good study.

   b. Let's look at a particular study. For example, here is what seems to be an oft-cited study on spontaneous miscarriages (according to Google Scholar it's been cited over 200 times).

   A few quick notes about this study:

   i. First, it's based on a population of women in China. But how generalizable is this to other groups of women in other parts of the world?

   ii. Also, I've seen some people online saying 25%-50% of all pregnancies end in spontaneous abortion. This study notes 7.9%. Who's correct? What are the most accurate and up-to-date statistics for the prevalence and incidence of spontaneous abortions?

   iii. And it should be noted the study itself differentiates between early pregnancy loss and spontaneous abortion: "Of the 618 detectable conceptions, 49 (7.9%) ended in clinical spontaneous abortion, and 152 (24.6%) in EPL." It's possible some people are confusing or conflating the two.

   c. Similarly, another study (pdf) cites spontaneous abortion rates of "14.0% in pregnancies without impaired fertility." Is this accurate?

   At the very least, there seems to be a fairly large disparity about the rates of spontaneous abortion between studies. Why is this?

   d. In any case, at a minimum, a literature review should be undertaken in order to assess the state of the literature as a whole on spontaneous abortion. Whether the lit review itself was well done or poorly done would be my next question.

4. There are issues with the logic of the argument.

   I don't see how the percentage of spontaneous abortions has any relevance to the personhood of zygotes. Let's say at some periods in history or among some people-groups as many as 99% of infants would die at birth. How would the sheer quantity of infant mortality at birth cast doubt on infants being persons? What do numbers have anything to do with human nature?

5. There are issues with what constitutes a spontaneous abortion.

   a. What is spontaneous or natural abortion? Medically speaking, it's a non-induced termination of pregnancy prior to 20 weeks' gestation or the delivery of a fetus weighing less than 500 grams. More popularly, it's known as a miscarriage. The 20 week cutoff can be variable; it is meant to reference viable gestational age.

   b. In addition, there are blighted ovums. Are blighted ovums considered in the percentage of spontaneous abortions? It's arguable blighted ovums aren't human in the first place, and as such it would be a red herring to include them in spontaneous abortion percentages as if they were pertinent to the debate over personhood, abortion, and the like.

   c. Likewise, there are differences between biochemical pregnancies, molar pregnancies, and clinical pregnancies. Are some or all of these included in spontaneous abortion figures? It's arguable not all should be included in miscarriage figures. For instance, again, why should we assume a molar pregnancy is a human being in the first place? What's the percentage of spontaneous abortions in clinical pregnancies?

6. There are issues with the causes and risk factors of spontaneous abortions.

   a. It's possible many if not most of the spontaneous abortions are caused by incomplete fertilization. As such, these incompletely "fertilized eggs" wouldn't be human beings.

   b. I've read the main cause for spontaneous abortion is genetic. Genetic abnormalities account for anywhere between 50%-70% of all miscarriages. The leading genetic abnormalities are autosomal trisomies (approximately 50%) and monosomies (approximately 20%), and the leading autosomal trisomy is trisomy 16. That is, trisomy 16 is the leading genetic abnormality leading to miscarriage. Full trisomy 16 is always lethal (although the mosaic form of trisomy 16 may not be lethal).

   c. Environmental causes are likewise prominent causes of spontaneous abortions. This includes smoking and alcohol, radiation, some medications (e.g. methotrexate), uncontrolled diabetes, certain autoimmune diseases (e.g. lupus), certain infections (e.g. chlamydia, gonorrhoeae, herpes, rubella).

   d. Age. Maternal age (as well as paternal age) is a leading risk factor for miscarriages. At approximately age 35 and above, there is a significant increase in risk of genetic abnormalities and thus spontaneous abortion. For example:

   The risk of a spontaneous abortion was 8.9% in women aged 20–24 years and 74.7% in those aged 45 years or more. High maternal age was a significant risk factor for spontaneous abortion irrespective of the number of previous miscarriages, parity, or calendar period. The risk of an ectopic pregnancy and stillbirth also increased with increasing maternal age.

   (Source)

   At least as I understand, people in developed nations are marrying at later ages. Presumably this means more people are conceiving and giving birth at later ages too. Could this modern development account for a significant portion of miscarriages? Perhaps it wasn't like this in the past.

   Indeed, we've only really been tracking miscarriage rates since about the 1970s at the earliest. So, although it may sound highly implausible, it's technically possible there were significantly fewer miscarriages in past centuries or millennia. It's not as if we have reliable stats on spontaneous abortions prior to the modern era.

7. There are issues in determining pregnancy and loss of pregnancy.

   a. There's a hormone known as beta-hCG which forms the basis for most pregnancy tests. However, hCG can result from other sources such as certain tumors. Thus it's crucial to track the level and pattern of hCG as well as correlate findings with ultrasound, not to simply take one or two measurements. Is this taken into consideration in miscarriage figures?

   b. Tests vary in their sensitivity as well as specificity. Tests can produce false positives and/or false negatives. See here for instance.

   Or as Dr. Allen Wilcox puts it in his book Fertility and Pregnancy:

   The problem with false positives is there are far more nonconception cycles (in which false positives might occur) than there are clinical conception cycles. Furthermore, nonconception cycles are not evenly distributed among women - they are more common in subfertile women. Thus, even a small false-positive error will lead to more apparent losses among less fertile women, thus creating an association of early loss with factors associated with infertility.

8. Finally, there are issues over death and grief.

   Let's say there are a certain percentage of zygotes who are spontaneously aborted. Why don't pro-life proponents mourn their loss?

   a. The most straightforward answer is because pro-lifers may simply not be aware that a certain percentage are lost to spontaneous abortion. Since many spontaneous abortions occur even before a woman is aware she's pregnant, then she wouldn't know. However, ignorance doesn't take away from the nature of what a zygote is. Ignorance doesn't make the zygote any less human.

   b. We tend not to mourn people we didn't know well or love. How well would we have known and loved a spontaneously aborted zygote? Besides, the fact that we do not mourn has no bearing on whether a zygote is a human being. We might despise someone like Bashar al-Assad, but still think he's a human being.

   c. As I mentioned above, full trisomy 16 is always lethal. If a spontaneous abortion was caused by a lethal genetic abnormality like trisomy 16, then it will die. But there's a difference between letting nature take its course, so to speak, and die, and attempting to save a life which can and should be saved such as in the case of a normal and healthy developing fetus.

   d. As I recall, Rick Santorum was severely mocked largely by liberals when he said he and his wife brought his stillborn son home, cradled him in their arms, and told their children their stillborn son was their baby brother. On the one hand, liberals fault pro-lifers for failing to mourn spontaneous abortions. But on the other hand, when pro-lifers do mourn, liberals ridicule them.

   e. I noticed Christopher Tollefsen has an article titled, "What We Should Do About Natural Embryo Loss."

There are other points we could bring up. But these should make for a decent start.