Pregnancy Guide – Abnormal Labor and Delivery

If all labors and deliveries were perfectly normal there would be little need for obstetricians. Many of them are complicated, to varying degrees, and must be skillfully handled. It is important that the pregnant woman be informed about some of these complications, too, in order that she recognize them if they occur, and realize what they portend. It is easier to understand and appreciate normality if we study the abnormal. And it is through cognizance of these problems that women will realize the advantages of being delivered by a good obstetrician at a good hospital.

Premature Rupture Of The Membranes

Rupture at Term. The membranes rupture spontaneously before the onset of labor in approximately one out of every ten cases. This, of course, can happen at any stage of pregnancy. If it happens at or near term, labor will almost surely ensue within 24 or 48 hours. This sequence of events is actually favorable, for labor in these cases tends to be slightly shorter than average.

Rupture before Term. If, on the other hand, the membranes rupture before term - say, in the sixth or seventh month - a somewhat different situation prevails. At this stage of pregnancy it is to be hoped that labor will not occur because of the high mortality rate among premature infants. Nevertheless there is no means known to modern medicine whereby the premature onset of labor can be prevented, and so in the majority of these cases labor will occur within a few days. The outcome, insofar as the baby is concerned, will depend mainly upon how much the baby weighs.

There remains a small but significant number of cases in which the membranes rupture two, four, six, or more weeks before term and then nothing happens. The longer the time interval before labor, of course, the better the baby's chances, but meanwhile there is the slight but constant danger of infection ascending from the vagina into the uterus and thence to the baby. Aside from abstaining from sex, douches, and tub baths, there is nothing one can do to prevent this infection. Not even antibiotics help. Nevertheless, many of these pregnancies progress without harm until the fetus becomes viable.

Premature Labor

The fetus may be expelled by the uterus at any time during pregnancy. If this occurs before the end of the twentieth week it is called an abortus, with no chance of survival; between the twentieth and the twenty-eighth weeks, an immature infant, with a poor chance of survival; between the twenty-eighth and thirty-sixth week, a premature infant, with a fair chance; and, after the thirty-sixth week, a term infant, with an excellent chance. One out of ten pregnancies terminate in the premature range.

Causes. In some cases premature labor is precipitated by maternal disease (such as toxemia), by twins, separation of the placenta, or rupture of the membranes. In half of the cases the cause is unknown.

Management. There is no sure way of stopping premature labor once it starts. Demerol and morphine have a temporary effect, but they cannot be used indefinitely. And ethyl alcohol is sometimes infused intravenously – invariably making the patient drunk and occasionally arresting her labor. After the labor process becomes irreversible, special care must be taken not to harm these tiny infants. The use of drugs and inhalation anesthesia is avoided in an effort to protect the baby from the hazards of narcosis. A certain amount of stoicism is necessary on the part of the mother in labor; spinal, caudal, or local anesthesia may be used for the delivery.

Prognosis. Prematurity is by far the most common cause of infant mortality today. Little is known about keeping these feeble infants alive. The survival rate is, as you would expect, directly related to the birth weight. A 2 ½ pound infant, for example, has but one chance in ten of surviving, whereas a 5 ½ pound infant has better than nine chances in ten. This issue is usually decided within forty-eight hours, and if the baby survives the first week its outlook is excellent.

Slow Labor

“False” Labor. When a woman says that she was in labor for three or four days, what does this mean? It means, quite simply, that the mother was in “false labor” for several days before the onset of true labor. No woman is permitted to remain in real, honest-to-goodness labor for longer than a maximum of twenty-four hours.

Causes. As a matter of fact, it is rare these days for labor to last longer than about twelve hours, even with the first baby. So what is the explanation of labors which go on for twelve to twenty-four hours? There are two main causes for this:

(1) There may be an element of disproportion between the size of the fetal head and the size of the maternal pelvis, i.e., the baby may be so large or the pelvis so small (or both) that it takes longer for the baby to be squeezed through the birth canal. Or

(2) the contractions of the uterus may be unduly weak, a condition known as uterine inertia.

Treatment. The former problem is discussed below, under the heading “Cephalopelvic Disproportion.” If the disproportion proves to be too great, a cesarean section must be done.

In the event of uterine inertia, the management is usually much simpler. The administration of minute amounts of Pitocin, the oxytocic hormone from the pituitary gland, almost invariably enhances the quality of the contractions so that labor is speeded up. In the occasional case where Pitocin fails, a cesarean may have to be resorted to. Other conditions which retard the progress of labor are too rare to mention.

All in all, with the more extensive use of Pitocin and cesarean section, obstetrics has entered an era in which the pregnant woman rightfully expects to have a reasonably short labor, shorter by several hours than her foremothers. This change has been partly responsible for a decrease in maternal and infant morbidity.

Dry Labor

The phrase “dry labor” is mentioned only because it has been ingrained in the lay mind. Actually there is no such thing as dry labor. The phrase is meaningless. It has become a widely accepted misconception that if the membranes rupture before labor or early in labor this will have some deleterious effect upon the baby. This is so far from the truth that most obstetricians actually make a point of rupturing the membranes early in most labors in order to speed up the process. There is no effect upon the baby from this practice other than to hasten its transit through the birth canal.

It is known too that the membranes constantly produce amniotic fluid at a rate of almost a pint an hour. Even if the membranes rupture a month or more from term, this fluid continues to be produced and to bathe the baby. Hence, no labor is “dry.”

Cephalopelvic Disproportion

If the mother's bony pelvis is unusually small or misshapen and the baby is average in size, it may be difficult or impossible to deliver the baby vaginally. If the mother's pelvis is average in size and the baby enormous, the same situation may prevail. This is called fetopelvic or cephalopelvic disproportion. The latter phrase is actually the more precise of the two, for the head (kephale in Greek) is the largest and least compressible part of the baby and hence the only part which need be considered in problems of this sort. Despite its relative lack of compressibility, however, the fetal head can and usually does change in shape during the course of labor. By this reversible process, known as molding, the head becomes elongated and its circumference thereby slightly reduced.

Diagnosis. The obstetrician estimates the size and shape of the patient's pelvis during the pelvic exam performed during her very first visit. Then when the pregnancy reaches term be estimates the size of the baby. In the vast majority of cases these estimates will reveal that the pelvis is sufficiently large to permit safe vaginal delivery. In rare cases the discrepancy between fetal and maternal measurements is so extreme that the obstetrician can proceed with a cesarean section before the onset of labor in the knowledge that vaginal delivery is impossible. X-rays of the pelvis must sometimes be taken just before or during labor in order to determine whether disproportion exists.

Trial of Labor. There remain a small number of cases in which this issue cannot be settled without an actual “trial” of labor. If sufficient progress is not made after a reasonable length of time, a cesarean section is performed. It may seem cruel to permit these women to undergo both labor and a cesarean section but with first babies especially, this is sometimes the only way of avoiding an unnecessary cesarean. And since cesarean section is still a major operation, one which has to be repeated with future pregnancies there is really no intelligent alternative.

The problem of disproportion is somewhat different when the fetus presents by the breech for in these cases the head is delivered last and therefore has no chance to mold to the shape of the pelvis. If disproportion is suspected in these cases, cesarean section is usually performed without a trial of labor.

Cesarean Sections

The origin of the term “cesarean section” is obscure. In the days of the early Roman emperors there was a law referred to as the “lex caesarii” (the law of the emperors), which proclaimed that women who died during pregnancy should be delivered immediately after death by abdominal incision. Such an operation on a living woman was unsafe and unheard of in those days. Quite possibly our term has its origins in this antique proclamation. The more popular belief that Julius Caesar was thus delivered is less tenable for the simple reason that his mother survived his birth.

Indications. A woman's first cesarean section is referred to as “primary,” her second as “secondary” and so on. The majority of primary cesareans are done for cephalopelvic disproportion. Others are done for placenta trevia and premature separations of the placenta, which are described below, for uterine inertia and for other rare conditions in which there would be greater risk to the mother or baby in vaginal delivery.

“Once a cesarean …“ Perhaps you have heard The expression, “Once a cesarean, always a cesarean.” It is an old obstetrical aphorism meaning that once a woman has a cesarean section, all of her future deliveries will have to be managed in this way. With rare exceptions, this is true. There are many reasons for this, the most important of which are these: When a uterus is cut in the course of a cesarean it becomes permanently scarred. This scar will always be weaker than the rest of the uterine wall; with every subsequent pregnancy there will be a small but definite (about 1 per cent) risk that this scar will rupture. Most of these ruptures occur in labor, when the scar is under stress. And since rupture of the uterus usually results in a dead baby and a very sick mother it is understandable not only that cesareans are repeated but also that they are usually performed a week or two in advance of the due date, before labor is apt to occur.

Number of Cesareans. Because of this risk of rupture of the uterus, sterilizations are often performed after three or more cesareans. The risk of rupture seems to be no greater with each succeeding pregnancy, but the patient undergoes this risk every time. Women have been known to have as many as twelve cesarean sections; they have taken twelve small chances of getting into serious trouble.

The Operation. Cesarean sections can be described as the simplest and at the same time the most dramatic of major operations. The abdominal wall is incised, vertically or horizontally, for a distance of about six inches; the uterine wall is incised, again vertically or horizontally, for about the same distance; the baby and placenta are delivered; and the incisions are then sewed up. The whole operation takes about an hour. The main source of concern is hemorrhage, for the pregnant uterus bleeds furiously when it is cut; but this rarely reaches serious proportions and, when it does, it can be counteracted by blood transfusions. Almost any type of anesthesia can be used; regional anesthesia is the most popular because of its lack of effect upon the baby.

The Recovery. Recovery from a cesarean entails a moderate amount of abdominal discomfort for about forty-eight hours, discomfort which is largely dispelled by analgesics. From the third day on, convalescence is rapid; the mother may nurse; the skin sutures are removed in about a week; and the patient is usually able to go home and take care of her baby on the eighth or ninth day.

Placenta Previa

Normally the placenta is attached high up on the interior wall of the uterus. Only once in about 200 cases is it attached low down in the region of the cervix. This latter condition is known as placenta previa, from the Latin word praevius, meaning “going before.” Sometimes the placenta is implanted in such a manner that it entirely covers the cervical canal (central placenta prevta); sometimes only the edge of the placenta infringes upon this opening (marginal placenta previa).

The Hazards. Since it is essential that the baby be delivered before its placenta, central placenta previa creates an obstetrically untenable situation which must be managed by cesarean section. The main hazard in these cases is hemorrhage. No matter where the placenta is located, the area of its attachment to the uterus is extremely vascular, for all of the maternal blood vessels nourishing the fetus must congregate there. As the cervix starts to dilate toward the end of the pregnancy and especially in labor, a placenta attached to the cervix will be gradually torn loose from its moorings. The combination of vascularity and tearing results in vaginal bleeding.

These simple facts explain at once the symptoms the dangers, and the principles of diagnosis and management of cases of placenta previa. The one and only symptom is intermittent painless vaginal bleeding in late pregnancy. The danger is that this bleeding will be massive and that it will occur without medical supervision. Fortunately the first episode of bleeding is rarely massive and can serve as a warning to the patient and the doctor.

Management. If the pregnancy is less than three weeks from term and placenta previa is suspected, the doctor will probably perform a pelvic examination in the operating room. If he feels the placenta covering most or all of the cervical canal be will perform a cesarean section immediately. The outlook for both mother and baby is good in these cases.

If the pregnancy is more than three weeks from term and placenta previa is suspected, the doctor will probably pursue a “hands-off” policy, for pelvic examination then may precipitate bleeding, while the fetus is still too small to be safely delivered. Various tests such as an ultrasonogram may be done to establish the diagnosis, but delivery will be postponed, if possible, until the fetus is term size. If the patient lives near the hospital she will be allowed home on limited activity. If she lives far away she may be kept in the hospital until delivery to protect her from the possibility of an episode of heavier bleeding.

Delivery. If profuse bleeding occurs at any time, the obstetrician will have to examine the patient, and if he finds a placenta previa he may have to do a cesarean section. If labor starts, the method of delivery will depend upon the amount of bleeding, which, in turn, will depend upon whether the labor is fast or slow and whether the placenta previa is central or marginal.

By no means does all late pregnancy bleeding stem from placenta previa. Although all such cases have to be handled with placenta previa in mind, often the source of the bleeding is much more trivial. And even if a placenta previa does exist, all well-trained obstetricians know how to handle it, so the risk to mother and baby is slight.

Premature Separation Of The Placenta

Another cause of bleeding in late pregnancy is premature separation of the placenta. This condition occurs once in about 100 deliveries.

Implications. Normally the placenta separates from the uterus in the third stage of labor, after delivery of the baby. Occasionally this separation begins to take place during the later months of pregnancy, before labor begins. The cause for this is unknown, although it occurs most often in patients with toxemia. Since the placenta is the fetus' sole source of oxygen and food, its premature separation will result in immediate fetal death if it involves a major portion of the placenta's surface. And since the site of attachment of the placenta to the uterus is so very vascular, its detachment will also cause bleeding from the uterus, which usually manifests itself vaginally.

Symptoms. Unlike placenta previa, premature separation of the placenta is characteristically associated with abdominal pain as well as bleeding, and it is soon followed by the onset of labor. In contrast to placenta previa, too, there is but one episode of bleeding, which does not stop until delivery of the baby.

Outlook. In most cases it is just an edge of the placenta which separates, a situation which can be handled expectantly with a good prognosis for successful vaginal delivery. If a large area of placenta is detached, the outlook is less hopeful. In the latter event, timing of the treatment is of the utmost importance to the fate of the baby. Sometimes the timing involves hours, sometimes mere minutes. Cesarean section will be done if the baby is still alive. The risk to the mother is never great, thanks to the modern blood bank.

Breech Presentation

Of every hundred term deliveries, the back of the baby's head (the vertex) comes first in ninety-five, the baby's buttocks (the breech) comes first in three, and the face, brow, or shoulder leads the way in two. The reason for this preponderance of vertex presentations is simply that this is the position in which the fetus best accommodates itself to the inverted pear shape of the uterus. This is fortunate since the headfirst position presents the fewest problems in obstetrical management.

BREECH PRESENTATION. The baby's buttocks will be born first. There will be no opportunity for the baby's head to become molded by the birth canal. (see image below)


The Risks. The risk to the mother from breech delivery is no different from that of vertex delivery, but the risk to the baby is increased threefold. The factors responsible for this greater fetal hazard are several. Since the head is not gradually squeezed through the birth canal, as with vertex presentations, it does not become molded and hence will be more difficult to deliver unless the pelvis is capacious. And since the baby's bottom fits less snugly than its head into the pelvis, there is a greater chance that the umbilical cord will insinuate its way around the fetus and into the vagina, an accident which imperils the fetus' supply of oxygen. The delivery itself is not complicated if the size of the pelvis is adequate .

Management. The incidence of breech presentation is considerably greater in the seventh and eighth month than it is at term. If your doctor discovers in the office that the fetus is lying breech down, he may turn it around by the simple, painless maneuver known as “external version,” which entails manipulating the fetus through your abdominal wall. As often as not, however, the fetus will turn back to its original position before your next visit. X-rays of your pelvis will probably be taken if you begin labor with the breech presenting, for it is vitally important to know in advance whether your pelvis is sufficiently large. If it is under average in size, a cesarean section will be done without a trial of labor.

Anyone can handle an uncomplicated delivery. And a good obstetrician will know how to handle the unusual situation. In the case of a breech, he will know when and how to turn the fetus, when to order X-rays and how to interpret them, when to do a cesarean section, and how to deliver the baby vaginally. So if you have a good doctor you have no need to worry about your baby's coming fanny first.

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