A Biological Background to Debate
FERTILIZATION, implantation, blastocyst, embryo, fetus, quickening, viability, abortion. These are all terms which recur throughout this book. They all relate to specific stages of fetal development from conception to birth. Their precise sociological, legal, and medical significance, however, is unclear to most laymen. In order to comprehend complex ethical, legal, and political issues of abortion the stages of fetal development should be clearly understood.
After ejaculation about one-quarter of a billion sperm cells are released in the vagina. The cells carry genetic information from the father. At the outset they. are largely packages of DNA-- the genetic thread of life-- just like the egg, which is the carrier of genetic information from the mother. The sperm cells actively move up the uterus into the woman's Fallopian tubes through which the egg proceeds from ovary to uterus and sperm from uterus toward the egg.
If there is no egg to be fertilized in the tube, the sperm will die in a few days. If the woman has ovulated, however, which she does once a month, and should the egg, whose life span is about two days, be alive--then one of these billions of sperms may penetrate the egg. DNA from the mother and father will be combined and the process called fertilization will have occurred. This newly fertilized egg or zygote will have within it the characteristics of both father and mother--one-half from each.
Now begins the nine-month process of fetal development. Slowly the fertilized egg starts its journey down the tube toward the uterus. As it proceeds it divides into two cells, then four, eight, sixteen, thirty-two, and so on.
The trip through the Fallopian tube takes about six days. During these days the woman will not know she is pregnant. The uterus is still empty. A curettage or scraping at this stage yields no evidence of pregnancy, although it prevents future development of the fetus.
It is at this moment that the ethical issues of abortion begin to arise.
1. The Issue: Pregnancy After Rape.
What are these complex tissues called the fetus?
What is the nature of its journey from conception to birth?
When does this tiny network of tissue become a living being?
Is it more justifiable to act to prevent pregnancy after rape now rather than later?
About one week after fertilization the tiny sphere of cells, often called the blastocyst, arrives in the uterus. Now begins a very critical stage in the struggle for survival. The blastocyst has only about seven days to implant itself in the soft spongy lining of the uterus; about a quarter of all blastocysts perish naturally.
2. The Issue: Prevention of Implantation.
Is the modification of the receptive tissues of the uterus so that implantation cannot occur comparable to direct removal or killing of the fetus?
The cells which burrow into the uterine lining are called the trophoblast. If they succeed in their mission, they produce critically important chemical hormones which signal the mother's glands to turn off her next menstrual period. In addition they keep the uterus quiet for the remainder of the pregnancy so that fetal development can proceed smoothly.
If the mission fails; menstruation occurs and the blastocyst is sloughed off. In fact, the purpose of the twenty-eight-day pill is to interfere with this signal so that any existing blastocyst is sloughed off.
After nestling into the uterine wall, the trophoblast becomes the placenta, or afterbirth. The opposite pole of the blastocyst becomes the embryo, or the fetus of later weeks.
3. The Issue: Hormonal Modification.
Is modification of the hormonal balance so that the blastocyst sloughs off through "normal" menstruation different from removal of the fetus or prevention of implantation?
Fourteen days of pregnancy have gone by, about seven in the Fallopian tube and about seven in implantation. Now the woman begins to realize that she may be pregnant. The anticipated menstrual period does not arrive. She may think it is just delayed a few days. But now, if she consults a doctor, the hormones produced by the blastocyst can be detected chemically in the woman's blood or urine and the pregnancy test will be positive.
After this second week of pregnancy, the rapid increase in complexity of the embryo begins. It is characterized by differentiation of the embryo into organs such as brain, heart, liver. By about six weeks, all the internal organs of the complete human being are present, though still in a rudimentary stage of development.
By the end of the eighth week, the embryo has been matured into what is generally called a fetus. Fingers and toes are fully recognizable. The skeleton starts to form. Though eyelids are not yet formed, the eyes are there. Simple reflex actions of the fetus can be detected. After this point no new major structures will be added. From now on the thrust of development will be toward growth and maturation of what already exists, rather than the creation of anything new.
4. The Issue: Interruption of Life.
With the change in name from zygote to blastocyst to embryo to fetus to infant, is here an abrupt major bio- logical change? Why at one stage do few question interruption of life, yet at another all question it?
At twelve weeks the fetus is about 31/2 inches in length, as shown in the twelve-week photograph. Bone and cartilage can be seen clearly. Fetal heart function can be detected by means of an electrocardiogram (EKG). Muscles and nerves have developed sufficiently so that the fetus moves its arms and legs vigorously. In fact, it has been doing these things for about two weeks. Mothers with experience from previous pregnancies may now be able to recognize the fetus kicking. Less experienced women, however, will probably not be aware of it for another four to six weeks.
Regardless of when the movements of the fetus are first felt, the event is called "quickening." The legal implications of this phenomenon will be discussed later, but this twelve- week stage is important to the medical issue of abortion. Before this point it is possible to perform an abortion by the relatively simple method of dilatation and curettage. After twelve weeks, however, doctors can no longer use this procedure with safety.
5. The Issue: Fetal Differentiation.
Is the twelve-week fetus so different from what it will be at twenty weeks that abortion at twelve weeks can be justified while induced death at twenty weeks is considered unjustifiable?
Between the twelfth and sixteenth weeks the eyes of the fetus are covered by eyelids. Nose, lips, mouth, ears, fingers, and toes are fully formed. Now the fetus may begin to suck its thumb. It will also be found to swallow the amniotic fluid in which it is lying. This is dramatically obvious if an X-ray photograph is taken. If a fluid opaque to X-ray is injected into the uterus, the twelve-week fetus will swallow it. The X-ray would show the fluid outlining stomach and intestines. It also reveals the stage of bone development at this point. Such X-rays are now frequently made in the uterus to discover the exact position of the fetus prior to giving it a blood transfusion for severe RH disease.
The twentieth week is another major milestone. Not only has half the pregnancy now passed, but from the twentieth week medical terminology no longer refers to the birth of the fetus as an abortion or a miscarriage. Now; any birth will be called a premature delivery. The fetus at this stage weighs about one pound and is about twelve inches long.
Until recently the term "miscarriage" referred to the spontaneous birth of a baby weighing less than two pounds, three ounces, or spontaneous birth before the twenty-eighth week. Now, about 10 percent of babies born before the twenty-eighth week or weighing less than two pounds, three ounces, survive. Obviously, these cannot be called "miscarriages" or "abortions."
Thus, in recent years, the term "miscarriage" has come to refer to births before twenty weeks, rather than before twenty eight weeks. In legal circles, however, the twenty-eight week point is still called the point of viability or ability to survive outside the uterus; but this legal definition is no longer in complete accord with up.to-date scientific information.
While the legal profession might for obvious reasons have to settle on a system of fixed definitions, the development of the fetus is obviously a continuous process. The ability to survive varies with the state of medical art and science. Two, five, or ten years from now scientific progress may well reduce actual viability from twenty weeks to eighteen to fourteen, perhaps even to twelve. If the law kept pace with such scientific progress it would have to change its definition of "legal abortion" regularly. After the twenty.eighth week little change in outward appearance occurs, except for increase in size. However, the complex development of various organs such as the brain accelerates greatly. [For comparative purposes, see the progression of fetal development in the photograph section.] Obviously, the more mature the fetus, the better the chances of its survival; but even this is not entirely exact. If the 266 days of pregnancy are prolonged beyond 280 or 290 days, then the fetus will be called neither "immature," "premature," or "mature," but "postmature." If not born in time, the chances of survival will once again begin to decrease.
In brief, then, regardless of the terms used, one thing is clear: Survival of the fetus depends on exquisite timing. There is a time factor in conception, a time for implantation, a time for the appearance of each organ and for its maturation, a time for birth, a time for the first breath, for the first cry. Each stage blurs imperceptibly into the next. But at all times, it also is clear, the potential for further development is always presen within the uterus-just as it should be throughout human existence.
Parallel to our knowledge of normal development runs ou increased knowledge of the abnormal: the things that may go wrong, what defects may occur and when. And with the knowledge also comes the knowledge of how to intervene in the process, when to transfuse the fetus, when to deliver it, how to protect it, how to assure its survival.
Yet to one question science can give no answer. Even the most accurate knowledge of the fetus cannot answer what value each stage of development has for society, for the mother or father, or in religious terms, for God.
The potential for future development is as great in the fertilized egg as in the blastocyst, as in the embryo, as in th fetus, as in the premature, as in the infant, as in the child. When is there a difference in this process that permits intervention or interference with life at one stage but not at an other? Why? At what stage? For what reasons?
In a democratic society the conclusive right or wrong--for political or social purposes-is only a composite of the individual conclusions of many people. These conclusions should be reached only after all available facts are known and only after full and extensive public and scientific discussions are held, to permit truly informed decisions to be made.
Chapter 4- The Statistical Background