By JOHN RICHARD SCHROCK
“Life” does not begin at fertilization. The human egg (ovum) and sperm are both living when they merge. Each carry half of each parent’s DNA and together have the potential to form a new individual. Therefore the question of when a human life begins is not a biological question, but a question of “personhood”—when do we bestow legal protections.
Most of our body cells are programmed to reproduce only a certain number of times. We therefore decline in function over time as we age. It is the sperm or egg cells we produce that allow our cell lineage to “live on” as half of the genetics of any descendant we produce. Human females have approximately 300,000 eggs present at puberty. Usually one is released each monthly cycle; the rest degenerate by menopause. Males do not begin sperm production until puberty, but those are in the hundreds of millions. In both cases, only a few may result in offspring and carry half of each parent’s genetics into a new generation.
Medical science and federal policy define a woman as pregnant when a fertilized egg implants in the wall of her uterus. However, there is a series of stages that begin before that and continue afterward: zygote–blastocyst–embryo–fetus. These stages are well-described online by the American College of Obstetricians and Gynecologists, the Mayo Clinic, the Guttmacher Institute and other medical websites.
There is a rare but serious condition where a sperm fertilizes an egg but it implants on the ovary, intestinal wall, or inside the Fallopian tube (90%+) and not on the uterine wall. This is an ectopic pregnancy and occurs in approximately two percent of pregnancies. The blood vessels that grow to nourish the embryo are not specialized like the uterine lining. This poses a serious threat of the mother bleeding-to-death. In this very dangerous situation, methotrexate may be administered to stop cells from growing. This ends the pregnancy and the tissues are absorbed by the mother’s body over 4–6 weeks
During the time from fertilization to reaching the uterine lining, there will be five or more days of development as it is wafted along the Fallopian tube. The fusion of sperm and egg resulted in a one-celled zygote. This then begins dividing into 6-to-10 cells by three days. In the next 2–3 days, it hollows out into a blastocyst. Cells on the inside wall will become the embryo. The outer layer will nourish and protect the embryo. This is the embryo’s contribution to the placenta that is also built from the lining of the uterus after implantation. It is important to realize that a portion of the cells derived from the fertilized egg develop into a substantial part of the placenta that is discarded after birth.
The American College of Obstetricians and Gynecologists agree that the establishment of a pregnancy takes several days and is not completed until a fertilized and developing egg is implanted in the lining of the woman's uterus. However, the 280 days (or 40 weeks) of “being pregnant” is calculated from the time of last menstruation which is perhaps two weeks before fertilization occurred, to provide an estimated date of delivery.
Up to half of fertilized eggs never implant and are shed with normal menstruation. This can be due to not enough or too much time since fertilization, deformities in development, or other problems. The federal definition of pregnancy beginning at implantation in the uterus becomes important in defining “morning after” pills as contraceptives. The Hyde Amendment has a provision that blocks the use of public funds to pay for abortion services. But funding is available for “drugs or devices to prevent implantation of the fertilized ovum.” However, a survey by the Alan Guttmacher Institute found that 18 states have legal provisions based on pregnancy beginning at fertilization.
Regular birth control pills (oral contraceptives) serve to inhibit ovary follicle development and ovulation (release of an egg) so there is no human ovum for sperm to fertilize. “Morning after” or emergency contraception pills contain the hormone progestin that reduces likelihood of pregnancy if taken within five days after possible fertilization. The “medication abortion” chemical mifepristone induces abortion by blocking the progesterone that maintains a pregnancy. It is followed by misoprostol that softens the cervix and causes uterine contractions to complete the abortion.
Today there is much public debate concerning these issues. We desperately need intelligent debate.
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John Richard Schrock has trained biology teachers for more than 30 years in Kansas. He also has lectured at 27 universities during 20 trips to China. He holds the distinction of “Faculty Emeritus” at Emporia State University.