The Signs of Pregnancy : Part 5

The Prospective Mother: A Handbook for Women During Pregnancy
by J. Morris Slemons

(Page 6 of 17)

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 also is subject to error for, as we have noted, the duration of pregnancy reckoned in this more exact 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 certain in its prediction, there are instances in which no other calculation can be made. A nursing mother, for example, may become pregnant before menstruation has been reestablished. Under these circumstances, obviously, 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, if for nothing more, 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 from month to month 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, on account of its size, it must rise 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 change in the figure which is noticeable to the patient, 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. The evidence gained from the position of the womb, like that afforded by the beginning of quickening, generally confirms the prediction made from the menstrual history; it serves only occasionally to 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, in all probability, 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, comprehensive statistics indicate that 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.