Spontaneous Abortion: A Pro-Life View
Why Are So Many Embryos Spontaneously Aborted
Very Early in Pregnancy? Is It Due to
“Selfish Chromosomes” or Design?
by Jerry Bergman, PhD
It is well known among embryologists that a large number of embryos are spontaneously aborted very early in the pregnancy (see Figure 1). This fact creates many questions and problems for couples. Is it better explained by evolution or by design? In these days after Roe v Wade was overturned, and abortion is very much in the news, the scientific facts about natural pregnancy, spontaneous abortion and miscarriage cannot be avoided.
Professor Laurence Hurst from the Milner Centre for Evolution stated in a press release on July 5 from the University of Bath:
About half of fertilized eggs die very early on, before a mother even knows she is pregnant. Tragically, many of those that survive to become a recognized pregnancy will be spontaneously aborted after a few weeks. Such miscarriages are … remarkably common.[1]
Figure 1. A nine-week-old human embryo from an ectopic pregnancy (one where the baby was developing somewhere other than the womb). If allowed to develop, both the baby and mother would die. Fortunately, ectopic pregnancies are relatively rare, (less than two percent of all pregnancies), and, if detected early, surgery most always saves the mother’s life. All states allow an abortion in this situation, and this has never been a problem. From Wikimedia Commons.
Furthermore, “natural human embryo mortality is high, particularly during the first weeks after fertilization, with total prenatal losses of 70% and higher.”[2] Hurst then implies that human reproduction is poorly designed and, as a result, is “extraordinarily wasteful,”[3] explaining this alleged poor design by invoking evolution.
Poor Design?
However, the reason for this loss is not poor design, as the University of Bath research implied, but is just the opposite, namely the result of good design. The developing embryo is exposed to constant chemical and background radiation assaults, as any pregnant mother knows, or should know. The post-birth human body has a highly effective repair system that mends 99 percent of the damage caused by these insults.[4] The zygote and early embryo contains DNA, a few organelles, and the machinery to enable cell division, but lacks the effective complex DNA and protein-repair systems employed by more developed embryos and fetuses.
Furthermore, the developing embryo has a mechanism that kicks in to cause a spontaneous abortion if development is not proceeding as required. This is recognized as a quality control system that reduces birth defects to the degree that, of those embryos carried to term, fully 97 percent are normal defect-free children. Of the three percent that have defects, many, such as orofacial cleft (cleft lip and palate), club foot, webbed toes, and even some heart defects, are minor or very treatable.[5]
Importantly, for healthy mothers who do not smoke nor use most prescription drugs at any time during their pregnancy, the birth defect rate in the developed Western nations is close to less than two percent.[6]
The Risk of Chromosome Defects
The new study on birth defects by Hurst concluded that a major cause of the problem is aneuploidy, an abnormal number of chromosomes. Aneuploidy results from either a missing or extra chromosomes.[7]
The most common aneuploidy is a trisomy, such as trisomy 21 which causes Down syndrome, but also trisomy 13 and 18. The main causes of trisomy include physical or chemical assaults combined with aging. Aging causes most aneuploidies that result from chromosome nondisjunction during meiosis. Chromosome nondisjunction of homologous chromosomes during meiosis causes excess or deficit chromosomes and affects mostly women.[8] Women who are 35 to 39 years old are approximately 4.5 times more likely to have a child with Down syndrome compared with women in the 25-to-29-years age group. This risk increases to 15.7 times for mothers age 40 years or older.
When a woman conceives past age 40, her eggs are over 40 years old, and, thus, have been exposed to over four decades of environmental insults. This is why later pregnancies are at much greater risk for an aneuploidy. Men produce new sperm during most of their reproductive life. This is one reason that the aneuploidy rate in sperm is only around one to four percent in men.[9] As Hurst observed,
Possibly more than 70% of oocytes are aneuploids and about 30% to 60% of preimplantation human embryos are [defective], the great majority being spontaneously aborted without a recognized pregnancy. In cases where the pregnancy is clinically recognized, around 10% to 20% result in early spontaneous abortion.[10]
Hurst’s research suggests that low levels of Bub1 protein may be a major factor in causing loss or gain of a chromosome in humans. Because Bub1 levels decrease as mothers age, the rate of aneuploidy in embryonic chromosomal problems increases. Furthermore, a heterozygous Bub1 mutation that reduces the Bub1 level also causes aneuploidy in oocytes, but not in sperm.[11]
Most all life-forms, such as most fish, do not require decades to store their eggs, thus, for this and other reasons, most non-human life does not have the same aneuploidy problem as do humans.
Creation and Pregnancy
The creationist worldview explains the loss of pregnancies as due to the fallen state of the world, thus the corrupt world physical environment adds to the mutation problem, which, in turn, affects the spontaneous abortion rate.
A sperm cell or egg cell (gamete) is not considered to be an individual human life because it is part of the mother or father’s body. Gametes do not have the required structures to divide, and will always die, usually within hours. Only a fertilized egg is a new life.
Although this is controversial, I would propose that only a viable zygote can be considered a new human life, because only a viable zygote can be defined as “alive” in the sense of being on a path to a human individual. The reason is that only a viable zygote can achieve cellular division. An aneuploid zygote, in the vast majority of cases, is not viable, thus it is reasonable to conclude it is not an individual human on the path to its own independent life. Most trisomy 13, 18 and 21 zygotes are not viable, and the only concern is the small percent that are viable—mostly trisomy 21 (Down syndrome). Trisomy due to transposition of part of a chromosome 21 would usually be viable, thus is not the concern here. As we all know, Down children can live well and are beloved by their families.
Cases of Certain Death
Figure 2. Possible locations of ectopic pregnancies. The most common extrauterine location is in the fallopian tube, which accounts for 96 percent of all cases. From Wikimedia Commons.
Ectopic pregnancies are ones where the embryo implants outside the uterus. If untreated, these can often cause the death of the embryo and the mother.
The likelihood of both spontaneous abortion and ectopic pregnancy (see Figure 2) are increased by many factors including cigarette smoking, drug abuse, aging, pelvic inflammatory disease, previous ectopic pregnancy, fertility treatment, tubal surgery, and fallopian tube surgery such as sterilization. Intrauterine device (IUD) use, while preventing pregnancy in the womb, is less effective in preventing a fallopian tube pregnancy.
The ‘mini-pill’, (progesterone-only pill), which affects the ability of an egg to move through the fallopian tube, also increases the likelihood of an ectopic pregnancy. Lastly, “emergency contraception” also increases such risks, because pregnancy can occur in the same cycle after trying to prevent pregnancy with emergency oral contraception.
Evolutionary Storytelling
Hurst attempts to attribute the spontaneous abortion rate problem to “selfish centromere theory.” This idea refers to a genetic element which, although deleterious, can increase in frequency in a population which has exclusively vertical transmission. But can a mutation be selfish? Hurst pictures mutations as schemers: “the mutation can ‘selfishly’ sneak into more than 50% of the eggs,” the press release tries to explain.
What Hurst noticed was that, in mammals, a selfish mutation that tries to do this but fails, resulting in an egg with one too many or one too few chromosomes, can still be evolutionarily better off. In mammals, because the mother continuously feeds the developing fetus in the womb, it is evolutionarily beneficial for embryos developing from faulty eggs to be lost earlier rather than be carried to full term. This means that the surviving offspring do better than the average.
The spontaneous abortion problem is well understood without resorting to some theory that, in essence, personifies centromeres or mutations.
Figure 3. A chromosome showing the centromere. From Wikimedia Commons.
The centromere is an important constriction point on a chromosome located where the cell’s spindle fibers attach. The two identical sister chromatids that make up the replicated chromosome are pulled to opposite sides of the cell as it divides (see Figure 3).
Centromeres and the spindle apparatus, with the kinetochore that winches the two sister chromatids apart, are extremely complex organs that scientists are still trying to understand. What’s surprising is not that failures occur, but that cell division works most of the time.
Summary and Conclusion
The “selfish centromere” theory was proposed in an attempt to relate the problem to evolutionary theory. A better outlook is to see quality control systems working to prevent defects.
Editor’s Comments: I know this is a touchy subject and that opinions may differ on some details. No matter one’s view, two things are clear: (1) No one can blame either parent for spontaneous abortion or miscarriage unless unhealthy behaviors increased the risk; (2) Intentional abortion is a totally different issue from spontaneous abortion.
Bible believers and all pro-life advocates say that “life begins at conception” as do many scientists (see list of quotes). Only a fertilized egg has an entire complement of human chromosomes. Only a fertilized zygote is totipotent (able to develop into a complete organism).
Whether a fertilized zygote that is guaranteed to abort because of aneuploidy or ectopic implantation is considered an individual human life may be a matter of opinion and terminology. Dr Bergman states his view that only a viable zygote can be considered a human life because it is incapable of dividing and surviving: “you cannot kill something that is already dead, which is what non-viable means.” He feels this is a common understanding for creation scientists.
Others may differ and call the unobserved spontaneous abortion an act of God, as they would a tragic miscarriage later in pregnancy. The head of a pregnancy support center I know points out that “the short term of life does not change that there was a life.”
Biblically, God creates life in the womb. He knows the number of days, or brief seconds, of our lives. Each life is created with a purpose and in His image… even those lost to miscarriage within minutes. Each one is valuable in His sight. At no time does God indicate that length of life determines value of life. If that were the case, then the older we are, the more alive or valuable we are.
Since length of life cannot be the measure of human worth, the question to focus on is, “What is the unborn?” Obviously, it is human. And as a human, it “has intrinsic value from the moment of creation throughout its life”—however long or short that life is. A human embryo is not, as some pro-abortion advocates used to say, based on Haeckel’s fraudulent “recapitulation theory,” progressing through earlier stages of evolution. The baby in the womb has its own genome, its own body, its own blood type, its own organs, and its own sex. The mother nourishes it through a complex placental system that doesn’t mix the identities of the two individuals.
Most likely there has been deterioration of the reproductive apparatus after sin entered the world. As part of the curse on their disobedience, God specifically told Adam and Eve that women would have pain in childbirth, and that man would sweat to gather food. Were there other physical consequences of sin and the curse? Was some of the curse a matter of deterioration over time, such as genetic entropy?
I would question Hurst’s number of the percentage of failed zygotes, because of the ethical and statistical problems with measuring such a thing worldwide for all of human history. But since there is nothing a doctor or parent can do about an unsuccessful zygote (and may indeed be unaware of it, since it may not even be observable), these are matters of academic and theological concern. Hurst says that the mother “probably never even knew her egg had been fertilised.”
I wrote for Evolution News (July 21, 2020) about quality control features at work during early embryology that indicate foresight and design. An embryo is not a clump of cells! It is an individual life on a programmed path to its own destiny. Every aspect of human sexual reproduction is marvelously intricate and superbly crafted. The evolutionary worldview cheapens human life and glorifies selfishness.
Bible believers, by contrast, are taught to love and respect one another as image bearers of God. The PRC director quoted above added some practical points that will determine our attitudes and actions on the abortion issue. “I have seen where great loss has brought about a tremendous ministry to others where compassion was needed,” she said—and doctors know that women who lose a pregnancy need a lot of support and help. In cases of stillbirth and spontaneous abortion, “As hard as it is, we need to embrace and trust that [God’s] purposes are good.”
Contrast pro-lifers with pro-abortion protestors screaming at justices and threatening violence, insisting on unlimited sexual pleasure, sacrificing the young for their own careers, treating unborn babies like trash. Thousands of quiet pro-life workers at PRCs do everything possible to help women work through unplanned pregnancies, offering free ultrasounds, advice, baby clothes and toys and moral support. Therefore, choose life.
References
[1] Just, Vicky. 2022. Why is it so hard for humans to have a baby? July 5. https://www.bath.ac.uk/announcements/why-is-it-so-hard-for-humans-to-have-a-baby/
[2] Jarvis, Gavin. 2016. Early embryo mortality in natural human reproduction: What the data say. F1000Research 5:2765 (doi: 10.12688/f1000research.8937.2), November 25.
[3] Hurst, L.D. 2022. Selfish centromeres and the wastefulness of human reproduction. PLoS Biology 20(7): e3001671, July 5. https://doi.org/10.1371/journal. pbio.3001671.
[4] Volkova, N., B. Meier, V. González-Huici, et al. 2020. Mutational signatures are jointly shaped by DNA damage and repair. Nature Communications 11(1):2169, May. https://doi.org/10.1038/s41467-020-15912-7.
[5] “Birth Defects.” 2022. Centers for Disease Control and Prevention, March 7. https://www.cdc.gov/ncbddd/birthdefects/types.html.
[6] NHS. 2019. Stop smoking in pregnancy. Smoking and your unborn baby. National Health Service, November 7. https://www.nhs.uk/pregnancy/keeping-well/stop-smoking/.
[7] Hurst, 2022.
[8] O’Connor, Clare. 2008. Chromosomal Abnormalities: Aneuploidies. Nature Education 1(1):172.
[9] Nagaoka, S.I., T.J. Hassold, and P.A.Hunt. 2012. Human aneuploidy: Mechanisms and new insights into an age-old problem. Nature Review of Genetics 13(7):493–504, Epub 2012/06/19, June 18. https://doi.org/10.1038/nrg3245, PMID: 22705668; PubMed Central, PMCID: PMC3551553.
[10] Hurst, 2022.
[11] Leland, S., et al. 2009. Heterozygosity for a Bub1 mutation causes female-specific germ cell aneuploidy in mice. Proceedings of the National Academy of Science U.S.A. 106(31):12776–12781, August 4. https://doi.org/10.1073/pnas.0903075106 PMID: 19617567.
Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.