LETTER VIII.. Duration of Pregnancy.

DURATION OF PREGNANCY.

Difficulties of Ascertaining it—Rules by which it is to be Known—At what Age can a Fetus Live?

The question relating to the duration of pregnancy is a difficult one. The general belief is, that the term lasts about nine calendar months. We hear spoken of “nine calendar months,” “ten lunar months,” “forty weeks,” or “two hundred and eighty days,” as indicating the length of this period.

It should be recollected, that there may be a material difference between nine calendar months and ten lunar months, as also between nine calendar months and forty weeks. Nine calendar months may fall short of forty weeks by from four to seven days. Thus, it may be two hundred and seventy-three days, two hundred and seventy-four, two hundred and seventy-five, or two hundred and seventy-six days, instead of two hundred and eighty days, or forty weeks.

What are the means by which the true duration of pregnancy, or an approximation thereto, may be established?

1. Cessation of the menses. This is by no means an infallible sign, as every one knows. The menstrual function, as we have already seen, often becomes obstructed from other causes than pregnancy. Conception may take place without the woman being regular. Thus, it may occur some months, even, after the menses have ceased from other causes. If, then, the reckoning should be made to commence at the time when cessation occurred, it would be found very fallacious in many cases. On the other hand, menstruation may occur one or more times after conception has taken place. So, also, it appears to be well established, that pregnancy may occur before menstruation ever appeared with the individual.

2. The period of quickening. This, too, is not a reliable source of reckoning the period of gestation. Quickening sometimes takes place, doubtless, before it is perceived. It takes place, also, at very variable periods, as I have elsewhere remarked; sometimes as early as the third month, sometimes not until the fifth, or, perhaps, the sixth. The range of quickening may be said to extend over a period of at least sixteen weeks. Thus it will appear that this mode of reckoning is by no means to be depended upon, although it often has been.

3. Peculiar sensations soon after conception. Some persons experience peculiar sensations within a day or two after conception. This is not true of every case, nor does the same individual experience these symptoms at each time of pregnancy. At one time she may have them, and at another time not.

4. Nausea and vomiting. These symptoms are too indefinite to enable us to form any just idea of the time when conception takes place. Some individuals do not experience them at all; some experience them very soon, almost immediately after conception; others not until the lapse of weeks, in some cases, probably months.

5. Coition. In the generality of cases it is impossible to know at what precise period pregnancy has commenced, because it is not known when the effectual coition took place. Now and then, however, such cases do occur; and in such instances, which are, on the whole, very rare, we find that the period of pregnancy varies somewhat as to its length.

Another method of reckoning has been to count from the time of the last menstrual discharge. Dr. Merriman, of London, has published a table of the births of 144 mature children, calculated from the day after the last menstruation was perceivable. According to this table

3 were born in the 37th week. 13 „ 38th „ 14 „ 39th „ 83 „ 40th „ 22 „ 41st „ 15 „ 42d „ 10 „ 43d „ 4 „ 44th „

Dr. Guy, of London, gives the following cases:

A case by Dr. Nixon 273 or 276 days „ Dr. Montgomery 280 „ „ Dr. Forster, of New York 283 or 285 „ A case before Lancaster Assizes 284 „ A case by Dr. Dewees 286 or 288 „ „ Dr. Desormeaux 290 „ „ Dr. Reid 292 or 293 „

The results of these cases are as follows:

Average of the seven cases 284 or 285 days. Minimum „ 273 or 276 „ Maximum „ 292 or 293 „ Range „ 16, 17, 19, or 20 „ Excess above 280 days, 12 or 13 days. Excess above nine calendar months, 16 or 17 to 19 or 20 days.

Thus it is plain that the period of gestation is more variable than some have supposed.

The same thing is also observed in animals, where, in general, a much more true record can be kept, than is possible in regard to the human species. M. Tessier, in France, caused a set of observations to be made on the duration of pregnancy in 160 cows, which commonly go nine months with young. His table is as follows:

3 brought forth on the 270th day. 50 „ 270th to the 280th day. 68 „ 280th to the 290th „ 20 „ 300th day. 5 „ 308th „ 14 „ 241st to the 260th „

There is, as will be seen in this table, a variation of sixty-seven days in the time a cow may carry her young.

A similar variation has been found in mares as cows, respecting the time of gestation. The same author—M. Tessier—made observations which were extended to 102 mares. The shortest period at which they brought forth was two hundred and forty-one days, the longest at three hundred and eight days.

Where there is no knowledge as to the precise time when an impregnation took place—and such is the fact in almost all cases with the human subject—a very good mode of reckoning is this: first ascertain the precise time when the menses last appeared, then reckon two weeks; at which time consider pregnancy as beginning. Nine calendar months, or forty weeks, which may vary somewhat from that period, will be about the time at which labor will ordinarily come on.

Another method is as follows: Quickening takes place at about the twentieth week; add twenty weeks more to the previous time, and we have an approximation to the truth. But, as I have elsewhere shown, the time of quickening is subject to a good deal of variation, namely, from the twelfth to perhaps the thirtieth week.

I think it will seldom be found to happen that labor occurs short of forty weeks, or 280 days, after the last appearance of the menses. But it is not out of place for me to inform you that medical men have varied considerably in regard to the duration of pregnancy. Thus, Dr. Guy has quoted five authorities, of greater or less eminence, to wit:

Sir Charles Clarke; 40 weeks—280 days.

Dr. Blegborough; 39, usually 40 weeks—273–280 days.

Mr. Pennington; 37 weeks; some, 40 weeks—259–280 days.

Dr. Gooch; a day or two before or after nine calendar months—271, 274, 275, or 278 days.

Dr. D. Davis; a day or two under nine calendar months.

The question as to the length of time it is necessary for a child to remain in the mother’s womb, in order to enable it to live, or to render it viable, as the term is, has been a very puzzling one to writers on medical jurisprudence. On this subject, I do not know that I can interest you in any better way than to give you some of the remarkable examples on record which go to establish the point.

“I have seen,” says Belloc, “a girl who, at birth, was only twelve and three quarters inches in length, whose skin was of a marbled redness, whose head was covered with down, whose nails were imperfectly formed, and who altogether bore a close resemblance to a young flayed rabbit. She was fed with the spoon for eight days, because she was unable to suck. Nevertheless, she is not only at the present moment alive, in her seventeenth year, but is likewise an extremely clever, amiable girl, above the middle stature, graceful in figure, and gay in her disposition. The mother could not fix with precision the date of her conception, but was convinced she was not at the term even of seven months. I considered her at six months, at the utmost.”

Dr. Guy, of London, mentions a case given by Dr. Rodman, in which he describes the mother as “more cautious in her decisions, accurate in her observations, and steady in her deportment than what is usually met with in society.” She had borne five children previously, and in this instance “was confident that the period of her gestation was less than nineteen weeks.” Premature labor came on in consequence of fatiguing exertions, and she was delivered of a living male infant.

“Not daring to allow the washing of the infant’s body, he was speedily wiped, and wrapped in flannel, with only an opening in the dress around his mouth for the admission of air; and by the time the dressing was over, the mother was ready to take him into the warm bed with herself. It is common, if there be much apparent weakness, to feed a child the first twelve hours after birth very frequently, yet, in this instance, although the child was weak, no feeding was attempted until beyond that time; the nourishing heat with the mother in bed was relied on. On the following day, the head, body, and extremities of the child were surrounded with fine cotton wool, pressed to appear like cloth, to the thickness of two or three folds, and over that the flannel, as before; and again the child was given to the mother in bed. His vital energy was so deficient, that even with this dress, of himself, he was unable to support the degree of warmth which was necessary to his existence. The heat of a fire was evidently injurious, as he soon became weaker when exposed to it; while the warmth of the mother in bed enlivened and strengthened him. Too much heat induced a sickly paleness of his face, with an obvious expression of uneasiness in his countenance; and the abstraction of heat, even by tardily undressing his head, brought on a nervous affection, or starting of the muscles all over his body. From seeing how these morbid affections were induced, the child was kept regularly and comfortably warm, by the mother and two other females alternately lying in bed with him, for more than two months. After this, he could be left alone from time to time, but was still undressed very cautiously, and only partially at any one time. It was not till the child was three weeks old that the length or weight of the body could be ascertained. The length was found to be thirteen inches, and the weight 1 lb. 13 oz. avoirdupois. It was extremely difficult to get the child to swallow nourishment the first week; the yellow gum soon came on, and the thrush seized him severely on the eighth day, and was not cured till the end of the third week. During the first week, he was fed with toasted loaf bread, boiled with water, sweetened, and strained through fine linen; in the second week, twenty drops of beef tea were added to the two or three tea-spoonsful of his mother’s milk, and in two days afterward he made exertions to suck. His mother’s milk was gradually substituted, at least in part, for the panada, though this was still continued occasionally, with a few drops of port wine. Under this careful management he attained the age of four months, at which time his health and excretory functions were peculiarly regular.”

Dr. Guy has arranged a table showing the lengths and weights of children reported to be born during the fifth and sixth months of gestation, with the assumed age and the probable age, according to estimates and observations which he had made and collected from various authors on the subject. It is as follows:

┌───────────┬───────────────┬───────┬────────┬──────────┬─────────────┐ │ Author. │ Length. │Weight.│Survived│ Asserted │Age according│ │ │ │ │ its │ Age. │to Estimates │ │ │ │ │ Birth. │ │ and │ │ │ │ │ │ │Observations.│ ├───────────┼───────────────┼───────┼────────┼──────────┼─────────────┤ │ │ Inches. │lb. oz.│ │ Days │ │ │Rodman │ 11–13 at 3 │1 13 │1 yr. 9 │133 │ 5 months│ │ │ w’ks. │ │ m. │ │ possibly.│ │Outrepont │ 13½ │1½ 0 │8 years │175 or 189│ 6 months.│ │Belloc │ 12¾ │— — │17 years│6 months │ possibly 5│ │ │ │ │ │ │ months.│ │Bucholtz │ 14 │1½ 0 │ 2 days │189 days │ 6 months.│ │Kopp │ 12¼ │2 0 │4½ days │182 │ 6 months.│ │Fleischmann│ 11½ │1 5 │ 8 days │168 │ possibly 5│ │ │ │ │ │ │ months.│ │Christison │ 13 │1 7 │8½ hours│167 │ possibly 5│ │ │ │ │ │ │ months.│ │Mr. Thomson│ 12½ │1 8¾ │3½ hours│5 months │ 5 months.│ └───────────┴───────────────┴───────┴────────┴──────────┴─────────────┘

Thus, it would appear, that it is possible for a child to live when born at about the end of the sixth month of fetal life, and, perhaps, somewhat earlier. But these cases must, I think, be rare, and not according to the general rule.

When a child is born, some idea may be formed respecting its age by the appearance it presents. A description of the signs of maturity and immaturity, founded upon that of two French authors, Foderé and Capuron, will serve to contrast the one with the other.

The signs of maturity are the following:

The ability to cry as soon as the child reaches the atmospheric air, or shortly thereafter, and also to move its limbs with facility, and more or less strength; the body being of a clear red color; the mouth, nostrils, eyelids, and ears perfectly open; the bones of the cranium possessing some solidity, and the fontanelles not far apart; the hair, eyebrows, and nails perfectly developed; the free discharge of the urine and meconium in a few hours after birth; and finally, the power of swallowing and digesting, indicated by its seizing the nipple, or a finger placed in its mouth.

The signs of immaturity, on the other hand, are the following:

The length and volume of the infant—much less than those of an infant in full term; it does not move its members, and makes only feeble motions; it seems unable to suck, and has to be fed artificially; its skin is of an intense red color, and traversed by numerous bluish vessels; the head is covered with a down, and the nails are not formed; the bones of the head are soft, and the fontanelles are widely separated; the eyelids, mouth, and nostrils closed; it sleeps continually, and must be preserved by artificial heat; and, lastly, it discharges its urine and meconium imperfectly, and often after a long interval.

You will, of course, readily comprehend that the appearances of children at birth, even of the same age of fetal life, must be subject to a good deal of variation. Some are much stronger than others, and the size and weight also varies a good deal. At one time a mother may have a very large, strong, and well-formed child, and at another a small and weak one. The size, however, does not determine the healthfulness of a child.