The Positive Signs—The Probable Signs—The Presumptive Signs: The Cessation of Menstruation; Changes in the Breasts; Morning Sickness; Disturbances in Urination; the Ductless Glands—The Duration of Pregnancy—The Estimation of the Date of Confinement—Prolonged Pregnancy.
Many puzzling questions occur to the woman who is about to become a mother. Most of these questions are reasonable and natural, and should be answered frankly; but a false conventionality has—until recently, at least—forbidden any open discussion of facts connected with childbirth. The inevitable result has been that, without experience of their own to guide them, prospective mothers have sought advice from older women, whose experience was at best very narrow, and whose views were often biased by tradition. Or, distrusting such sources of information, they have consulted technical medical works that they could not understand. Either of these methods is very likely to result in misinformation and to cause unnecessary anxiety.
Yet no one need be alarmed by a plain, accurate account of Nature's plan to provide successive generations of human beings. Some trustworthy knowledge of a process so fundamental should be part of every person's education; it is especially helpful to women who are pregnant because it affords a rational basis for hygienic measures that they should adopt. A popular work, however, no matter how frank and helpful it may be, will not enable one to dispense with professional advice. For the prospective mother, no counsel is more important than this: Put yourself at once under the care of a physician.
Pregnancy Is Natural, But Medical Supervision Matters
Insistence on the importance of medical advice should not be taken to imply that pregnancy is to be regarded as other than a normal process. Its dangers are comparatively slight, as we should expect, since the property of all living matter to reproduce its kind is both fundamental and essential; the continuance of living creatures in this world, plants as well as animals, depends upon the Reproductive Process.
And yet, natural as it is, pregnancy may be attended by complications. Such complications, though happily rare, are to be guarded against in every case, and that may be most effectually done if patients are taught to remain under competent medical supervision from the time of conception until several weeks after the child is born. This precaution greatly reduces the frequency of annoyances during pregnancy and also assists materially in conducting a birth to a safe conclusion. Moreover, if this advice is followed, when complications do arise, they will be recognized and dealt with promptly; they will not be permitted to grow more serious until, perhaps, they may jeopardize the life of the mother or the child or both.
Recognizing Pregnancy: Reliability of Evidence
The initial symptoms of pregnancy are so widely known that in most instances the prospective mother herself makes the diagnosis shortly after conception has taken place; but now and then pregnancy advances for several months unrecognized and is then detected by a physician who has been consulted on account of symptoms which the patient has incorrectly attributed to some other condition.
On the other hand, women sometimes suspect that they are pregnant when they are not; and such mistakes occur because certain symptoms which are implicitly trusted by the laity as manifestations of pregnancy are occasionally associated with conditions quite foreign to it. It is clear that one interested in the matter must know not only what the manifestations of pregnancy are and when they appear, but also how far the evidence that they give is reliable.
The signs of pregnancy may be classified, according to their reliability, as presumptive, probable, and positive. The doubtful evidence appears first and the infallible proof last. No one need be surprised, therefore, if, when her suspicion is first aroused, she is unable to decide positively whether she is pregnant. Physicians of broad experience, possessed of facilities for observation which their patients cannot employ, may find it necessary to make more than one examination before they commit themselves to a definite opinion; in some cases, though very rarely, they must wait for two or three months to be able to do this.
The Positive Signs
The earliest absolutely trustworthy manifestation of pregnancy is the motion of the fetus. The perception by the mother of these movements, which is spoken of as “quickening,” generally occurs toward the eighteenth week, if she has been told to watch for them; otherwise they may pass unnoticed until the twentieth week or later. At first the motion, felt in the lower part of the abdomen, is very gentle; it has been variously likened to tapping, or to quivering, or to the fluttering of a bird's wings. As time goes on the movements grow stronger and occur more frequently; they are, however, perceived but rarely throughout the day and seldom interfere with sleep. Occasionally women are annoyed by the sensation and complain that the child is hardly ever quiet. Even these troublesome movements are never a cause for anxiety; but prolonged failure to feel motion after it is once well established should be reported to the doctor.
In the first pregnancy the passage of gas through the intestines may be mistaken for quickening long before the movements of the child are really perceptible; but those who have once experienced quickening will not be deceived. Whenever women who have borne children are in doubt the sensation is almost surely not quickening. Furthermore, in any doubtful case, the motion should be observed by a physician before being accounted a positive sign of pregnancy. This precaution will scarcely delay an absolutely positive diagnosis, since the proper method of examination reveals these movements to the physician almost as early as the patient feels them.
About the time these movements become perceptible another positive sign is available. The physician whose ear has been trained to catch such sounds when he listens over the lower part of the mother's abdomen will hear the fetal heart-beat. Other sounds may be audible there, but the character and the rate of the heart-sounds are distinctive. Since the child's heart beats almost twice as fast as the mother's, under ordinary conditions it is impossible to confuse one with the other, The mother never feels the beating of the child's heart, but occasionally she will mistake for it the throbbing of her own blood vessels.
Ability to hear the fetal heart not only provides a means of confirming the existence of pregnancy in doubtful cases, but also enables the physician to reassure his patient if she fails temporarily to feel the child move. Sometimes the presence of twins is recognized in this way. Toward the end of pregnancy the heart sounds are also of material assistance in determining what position the child has permanently assumed.
There is a third positive sign of pregnancy to which the physician has recourse, but generally it is inapplicable as early as those already mentioned. In the latter months of pregnancy it is possible to outline the child through the mother's abdominal wall. Although this procedure adds little or nothing to our resources for making an early diagnosis, the information it ultimately affords proves one of the greatest aids in the practice of obstetrics.
The Probable Signs
Phenomena for which the child is responsible supply the most trustworthy evidence of pregnancy; and these phenomena alone are accepted as positive signs. But there are earlier manifestations which intimate very strongly that conception has taken place. Shortly after pregnancy has become established changes begin in the uterus, and soon reach the point where they may be recognized by a simple examination which enables the physician to express an opinion little less than positive.
As one result of pregnancy, the supply of blood is increased to all the organs concerned with the reproductive process. Partly because of this congestion and partly because of embryonic development, the uterus becomes altered in a number of ways. Although these changes occur regularly in pregnancy, they may occur when the womb is enlarged from other causes; therefore, if a physician should make the diagnosis of pregnancy whenever they were found, he would make it somewhat too frequently. With a little patience, however, he excludes the chance of being misled; a second examination, approximately four weeks after the first, will generally place the existence of pregnancy beyond question, for under normal conditions the degree of enlargement which takes place in a pregnant womb during a given interval is absolutely characteristic. It is generally supposed that some characteristic change occurs in the blood during pregnancy, but thus far none has been demonstrated.
The Presumptive Signs
Although women are most often led to suspect that they are pregnant by symptoms which are of such doubtful significance that they must be regarded as merely presumptive evidence, the practical value of these symptoms is attested by the fact that subsequent developments rarely fail to confirm the suspicion. Perhaps they prove misleading once or twice in a hundred cases; the number of mistakes is small, because the diagnosis is commonly made not from only one of these doubtful signs but from a group of them. In order of importance the doubtful or presumptive signs of pregnancy are these: (1) cessation of menstruation, (2) changes in the breasts, (3) morning sickness, (4) disturbances in urination.
The Cessation of Menstruation
The failure of menstruation to appear when it is expected is nearly always the first symptom of pregnancy to attract attention, and, as a rule, when this happens to healthy women during the child-bearing period, which usually extends from the fifteenth to the forty-fifth year—it may be taken to indicate that conception has occurred. But there are exceptions to this very good rule. Besides pregnancy we are acquainted with several conditions that cause temporary suppression of menstruation; and to understand its significance we must learn something of the menstrual process itself.
Menstruation is a function of the womb and in all probability is brought about through the influence of the ovaries. The bleeding, popularly regarded as the entire menstrual process, is, in fact, indicative of only one of its stages; the others give rise to no symptoms whatever. What the stages in the menstrual process are, what relation they bear to each other, and what the significance of the whole process is, are problems that have been solved with the aid of the microscope.
In this way the mucous membrane lining the womb has been studied both at the time of the periods and in the interval between them, and we have learned that it is constantly undergoing changes intended to facilitate the reception and the maintenance of an embryo. Anticipating these duties the mucous membrane receives a more abundant supply of blood; it also increases in thickness and all the structures which enter into its composition become more active.
Unless conception takes place these preparations, which represent the most important phase in the menstrual process, are without value; and therefore failure to conceive means that the mucous membrane will return to the same condition as existed before the preparations were begun. The congestion is relieved by rupture of the smallest blood vessels, and there follow other retrogressive steps which completely restore the various structures to their former state. Then there is a pause, though it is not long, until preparatory changes are again initiated, or, as we say, another Menstrual Cycle is begun. Each cycle lasts twenty-eight days, and includes four stages, namely, a stage of preparation, of bleeding, of restoration, and of rest.
Although pregnancy may become established at any time during the interval between the periods of bleeding, it is more likely to be established just before a period is expected or shortly after it has ceased. Furthermore, whenever conception does take place, the preliminary preparations for the reception of the embryo are followed by much more elaborate arrangements for its protection and nutrition. Under these circumstances the hemorrhagic discharge does not appear.
Were there no other condition to bring about the cessation of menstruation, the diagnosis of pregnancy would be greatly simplified. But any one can appreciate the fact that diseases of the womb may interfere with the menstrual process. Menstruation is influenced, also, by the ovaries. As a result of age, for example, the ovaries undergo changes which invariably bring about the permanent cessation of menstruation, called the menopause. This event occurs prematurely if both the ovaries are removed by operation. In view of these facts it is not surprising that sometimes ovarian disorders abolish menstruation. An impoverished state of the blood, or nervous shock and strain, or constitutional debility may also interrupt the regular appearance of the menstrual discharge.
The value of menstrual suppression as an evidence of pregnancy is not, however, to be discounted to the extent that we might expect. This is true because the ailments which lead to confusion are relatively infrequent, and also because they exhibit characteristic symptoms which are foreign to pregnancy. Often these symptoms are obvious to the patient herself; if not to her, they will be obvious to her physician.
It is about the doubtful cases, naturally, that a professional opinion is sought, and on that account physicians are perhaps inclined to overestimate the difficulty women have in learning for themselves whether or not they are pregnant. As a matter of fact, it is unusual for a prospective mother to fail to reach a correct decision—a decision for which she relies chiefly upon the suppression of her menstrual periods.
It is doubtful whether menstruation ever continues after conception has taken place. Instances in which the menstrual function is believed to persist are not uncommon, and yet in all probability the discharge regarded as menstrual has a different origin. In most cases it should be interpreted as meaning that there is some danger of miscarriage. Since miscarriage often occurs about the time a menstrual period would ordinarily be expected, there is unusual opportunity for confusing the symptoms.
At all events women much more frequently in suspecting that they are pregnant than in overlooking the condition. Indeed, pregnancy is not likely to be overlooked unless menstruation has been irregular or suppressed for a month or more previous to conception. Thus, in the case of nursing mothers in whom menstruation is already suppressed and who are, moreover, deprived of certain evidence that the breasts give, pregnancy may sometimes advance several months before it is recognized.
The Changes in the Breasts
Various sensations in the breasts are accepted by women as a reliable sign of pregnancy; thus throbbing, tingling, pricking, or a feeling of fullness will be mentioned by one mother or another as having given her the first intimation that she was pregnant. A few women also find their breasts become tender immediately after they have conceived; this may be so marked that they cannot bear pressure. But unless such symptoms are accompanied by definite, visible changes, they have no value as signs of pregnancy.
About the end of the second month the nipples become larger and more erectile, and deepen in color. The pigmented, circular area of skin which surrounds the nipple, called the areola, also darkens. The shade that the areola assumes will vary according to the complexion of the individual, growing darker in brunettes than in blondes. Ultimately, within this pigmented circle a number of elevated spots appear about the size of a large shot. These spots betray the presence of tiny glands always located there which, on account of the better state of nutrition during pregnancy, grow larger, and generally become visible.
Usually, after two menstrual periods have been missed the breasts increase in size and firmness, and often the veins which run just beneath the skin stand out conspicuously. Before very long it is possible to squeeze from the breasts a fluid which many persons believe to be milk, though it is really colostrum, a substance that resembles milk but very slightly. At first colostrum is a clear, white fluid, but in the later months of pregnancy it becomes yellow and cloudy.
None of the changes in the breasts are absolutely characteristic of pregnancy; even the secretion of colostrum has been noted in association with various other conditions. Furthermore, as a sign of pregnancy the presence of colostrum is totally deprived of value in the case of a woman who has recently nursed an infant, for a small quantity of milk or colostrum often remains in the breasts for months after the infant is weaned. In general, however, women who have not been pregnant before should assume that they have conceived if, after missing a menstrual period, they note the characteristic changes in the breasts.
Morning Sickness
Soon after conception many women suffer from nausea and vomiting, especially on rising in the morning. “Morning sickness” usually passes off in a few hours, although it may be more persistent. Perhaps this manifestation occurs more frequently in the first than in subsequent pregnancies, but certainly one-half, and probably two-thirds, of all prospective mothers suffer from it. Usually the nausea begins just after a menstrual period has been missed, and ceases about the third month or a little later.
But morning sickness is never counted an indication of pregnancy unless taken in conjunction with other symptoms, for individuals who are not pregnant may also suffer from nausea in the morning. On the other hand, a number of prospective mothers escape morning sickness altogether, and a few experience nausea at other times of day.
Disturbances in Urination
It is not an uncommon belief that some characteristic change occurs in the urine shortly after conception. But this is not true; at least no change is revealed by any method of analysis known at present. Some patients have difficulty in urination, and a few experience discomfort with it. All the bladder symptoms usually disappear about the fourth month, but become prominent again toward the end of pregnancy.
The inclination to empty the bladder more often than usual may be due merely to nervousness, and therefore cannot be regarded as a trustworthy sign. While in no way connected with the kidneys, it is a direct and natural result of pregnancy. Since the womb enlarges and tilts forward at a more acute angle than formerly, it presses against the bladder, giving the same sensation as when the bladder is distended with urine.
The Ductless Glands
Our bodies contain a number of small organs architecturally like glands, but because they are not supplied with the channels or ducts through which glands ordinarily empty themselves, anatomists hesitated to classify them. Ultimately, however, they learned that the secretion is absorbed directly by the blood. The fact that the products of these glands enter the circulation correctly indicates their important character; they profoundly influence the way in which all our organs work.
One of the functions of the ovaries places them in this group of glands. Every month there appears in one ovary or the other a slowly growing, spherical structure which at the height of its development attains a diameter of about a half-inch and after having served its purpose gradually disappears. The corpus luteum, as this is called on account of its faint yellow color, plays a fundamental part in providing the requisite stimulus for those changes which occur in the uterus during menstruation. And its activity during pregnancy is even more essential; when conception takes place the structure grows to more than twice its usual size.
Other ductless glands include the adrenals, located near the kidneys, the pituitary body at the base of the brain, and the thyroid with the para-thyroids at the front of the neck. Almost certainly while pregnancy exists these glands perform more than their usual task and they increase in size, though, on account of their location, the enlargement is imperceptible except in the case of the thyroid gland, which not infrequently causes a slight fulness of the neck that continues until the end of pregnancy and then subsides.
It must be said that our knowledge of the influence of these glands upon the course of pregnancy is meager indeed. A few established facts, however, plainly point toward an intimate relationship between the ductless glands on the one hand, and the reproductive organs on the other. The pituitary body, for example, contains a substance acting powerfully upon the uterine muscle. Without multiplying illustrations it is perhaps sufficient to express the conviction that with a broader knowledge of the ductless glands physicians will acquire the means to reach a positive diagnosis of pregnancy at an earlier period than is now possible.
Although the presumptive signs which we have considered by no means exhaust the list, all the others are totally untrustworthy. Each of the more reliable symptoms, as we have seen, must be accepted cautiously; but taken altogether, except in very unusual cases, they may be relied upon. If, for example, menstruation has previously been regular and then a period is missed, the patient has good reason to suspect she is pregnant; if the next period is also missed and meanwhile the breasts have enlarged, the nipples darkened, and the secretion of colostrum has begun, it is nearly certain that she is pregnant; whether morning sickness and the desire to pass the urine frequently are present is of no importance. But the most characteristic evidence, we must remember, is not available until the eighteenth or twentieth week; then the signs of pregnancy are unmistakable.
The Duration of Pregnancy
After the existence of pregnancy has become assured, perhaps the greatest interest centers about the date upon which the birth may be expected. Even to approach accuracy in this prediction the prospective mother must be familiar with certain facts which she will always observe, but which, unless she appreciates their importance early in pregnancy, she may fail to record or to remember. In a few cases, however, such exceptional information as knowing the date of conception does not lead to an absolutely accurate prediction. But the deviation from the rule will be understood only after we understand the rule itself, which is based upon what we accept as the average duration of human pregnancy.
The period of gestation for each variety of mammal is determined by the time required for embryonic development to reach the point where the young may live independently of the mother. This point is reached more quickly with small animals. The mouse, for example, generally brings forth its young in three weeks, whereas the pregnancy of the elephant lasts two years. In human beings, counting from the time of conception to the time of delivery, pregnancy continues approximately 273 days. This is merely an estimate calculated from hundreds of cases in which there was no question as to the underlying facts. Individual cases vary notably; two women may become pregnant on the same day and yet not necessarily be delivered at the same date.
Irregularities in the duration of pregnancy are not limited to man. Thus, while the mean period of gestation in the rabbit is thirty-one days, it may be either shorter or longer by as many as eight days. Similar variations occur in the pregnancies of all animals, and are, moreover, notably greater among larger animals. For instance, the mean period of pregnancy in the cow is 285 days from the time of conception. This fact notwithstanding, a competent observer found that, of 160 cows, 67 were delivered before the 280th day; 68 between the 280th and the 290th day; and 25 after the 290th day. Although nothing unnatural was observed in any instance, the first animal was delivered 67 days before the last, and in 5 instances gestation continued 308 days.
In ancient times it was believed that the duration of pregnancy was of even more uncertain length in man than in the lower animals; but thirty-nine weeks are now accepted as the average duration of the human pregnancy when reckoned from the day of conception. As this date is seldom known, it is most convenient to reckon from the first day of the last menstrual period. Estimated in this way its average duration is 280 days. As this period corresponds to ten menstrual cycles, physicians prefer to describe pregnancy as lasting 10 lunar months of four weeks each. This is equivalent to 9 calendar months, in terms of which its duration is popularly stated.
The Estimation of the Date of Confinement (Due Date)
Since pregnancy is not an absolutely fixed period, we possess no reliable means of predicting the exact day when it will end. The most satisfactory method of prediction consists in counting forward 280 days from the beginning of the last menstruation, or, what gives the same result, counting backward eighty-five days from this date. To make the calculation in the simplest way we count back three months and add seven days; this addition is made because seven days generally represents the difference between three months and eighty-five days. If the last menstruation, for example, began on October 30th, we count back three months to July 30th and add seven days, which gives August 6th as the probable date of confinement.
A prospective mother should remember that this prediction is no more than approximate. The calculation does not give the exact date of delivery more than four or five times in a hundred cases. It is accurate within a week in half the cases and within two weeks in four-fifths. We also know that delivery is somewhat more likely to occur after the expected date than before it. But perhaps we shall get the clearest idea of the accuracy of the rule, or better still of its inaccuracy, if we imagine twenty patients to have the same predicted date, all of them giving birth to mature infants. The chances are that only one of these patients will be confined upon the day predicted; nine will be confined before and ten after it. In all probability five of those who pass the predicted day will be delivered within a week and four others within the second week, while the twentieth patient will not be delivered until three weeks or more have elapsed.
Such results clearly indicate our inability to make accurate predictions even though pregnancy is normal in every way. Whenever patients pass their expected date uneventfully, if they will bear in mind that the fault lies with the method of prediction and not with the pregnancy, they will often be saved anxiety. Frequently such discrepancies are attributable to a false assumption, for our rule always assumes that the conception took place immediately after a menstrual period. While this is generally true, the number of cases in which it occurs just before the period to be missed is by no means inconsiderable, and in these we should not expect pregnancy to end until two or three weeks after the day predicted by the rule.
Occasionally patients know the precise day upon which conception took place, and prefer to estimate the day of confinement from that rather than from the beginning of the last menstruation. They may do so by counting back thirteen weeks from the day of conception; but this method is subject to error, for the duration of pregnancy reckoned in this manner is not constant. Such a calculation rarely offers any advantage over that made from the menstrual record.
Another method of estimating the date of confinement is based upon the assumption that fetal movements are first perceived by the mother toward the eighteenth week of pregnancy; and in consequence twenty-two weeks generally elapse between quickening and the day of delivery. Although such a calculation is far from accurate, there are instances in which no other can be made. A nursing mother, for example, may become pregnant before menstruation has been reestablished. Under these circumstances, the date of confinement cannot be estimated in the ordinary way, and it is then especially important to know the first day on which the fetal movements were felt. Furthermore, it is helpful to note this date in every case, since it serves to confirm the prediction made from the menstrual record.
Besides the two methods just described, which are alike in that they require the patient herself to make the necessary observations, there is a third method of estimating how far pregnancy has advanced, by which the physician is enabled to draw his own conclusions. This method is based upon the fact that the womb enlarges during pregnancy at a constant rate. Up to the end of the third lunar month it cannot be felt through the abdominal wall; but in the course of the fourth month, it rises into the abdominal cavity. At the beginning of the sixth month the top of the womb is at the level of the navel, and at the ninth reaches the ribs. The diaphragm then prevents the womb from going higher; and two or three weeks before the end of pregnancy it drops several inches, causing a noticeable change in the figure, since her skirts hang somewhat lower than before. From this time on she is more comfortable, because the lungs are not crowded, and there is less interference with breathing.
These alterations in the position of the womb indicate very satisfactorily the month to which pregnancy has advanced, but not the week and much less the day. They do not afford a more accurate means of predicting the date of confinement than does quickening. Generally they confirm the prediction made from the menstrual history, and only occasionally correct it.
Prolonged Pregnancy
Since birth does not occur in many cases until the predicted date has been passed, it will be helpful even at the cost of repetition to sum up what we know in explanation of such unfulfilled predictions. They are to be explained sometimes by uncertainty as to the beginning of pregnancy, as for example, by the supposition that conception took place shortly after the last menstrual period, whereas it actually occurred two or three weeks later. In a few instances, however, errors of observation or of calculation will not account for false predictions.
It is generally admitted that second pregnancies average somewhat longer than first pregnancies; one series of statistics indicates that the duration increases slightly with each pregnancy up to the ninth and decreases after that. Pregnancy is protracted more frequently in healthy women than in those who are not, and again more frequently in those who are inactive than in those who work. With twins, contrary to the popular belief, pregnancy is apt to end before, not after, the expected date. The sex of the child has no influence upon the duration of pregnancy.
As we might expect, individuality is also a factor in this problem. Thus, the period of gestation with some women is regularly longer, with others habitually shorter than the accepted average. Until experience has demonstrated their existence, generally, such peculiarities are overlooked. But occasionally they may be detected from knowledge of the interval between the menstrual periods; an unusually long interval between them, for example, would lead us to anticipate a protracted pregnancy.
Any delay after the expected date of birth has arrived taxes the patience of the prospective mother. The fact, however, that more than 280 days have passed since the last menstruation, does not necessarily mean that a patient has gone “over time.” Such a question can be decided solely from the weight and length of the child. Judged in this way, once in several hundred cases pregnancy may be fairly called prolonged. Even in these rare instances an examination about the time of the predicted date makes it clear whether pregnancy should be artificially ended or be allowed to proceed to its natural conclusion.
Helpful tools: Try our Pregnancy Due Date Calculator to estimate your EDD using LMP, conception, or ultrasound. For symptom timelines, read Pregnancy Symptoms Week by Week, and for validation of dating methods, see How Accurate Is a Pregnancy Due Date Calculator?. For professional guidance, consult trusted resources such as ACOG and Mayo Clinic.