MATERNAL IMPRESSIONS.—Contrary to all that we know of heredity, the conviction prevails among the laity that the character of a child depends greatly upon the mother's surroundings during pregnancy: this is the doctrine of maternal impressions. As is usual with superstitions, this one emphasizes the unfavorable possibilities and holds that the unborn child may be affected by the mother's unhappy thoughts or maimed by her mental distress if she is exposed to unpleasant sights. For this belief there is no foundation; the cases often cited in its support may be fully explained on the grounds of coincidence.
With the possible exception of such individuals as are spending their lives in solitary confinement, there is scarcely a human being who has not in the course of nine consecutive months some untoward physical or mental experience which engraves itself upon the memory. Prospective mothers are not apt to be exempt from a rule so general in its application, but if by good chance one happens so to be she will hardly fail to hear of the misfortune of others, which, according to the doctrine of maternal impressions, may be equally effective in interfering with the proper development of the child. We should then rightly expect most, if not all, babies to be "marked"— clearly a situation which does not prevail.
In order to learn how frequently prospective mothers may have disagreeable experiences which they fear will affect the formation of the child, I have lately asked the patients whom I have attended, "Was there any incident during your pregnancy to which you could have attributed the infant's condition, had it been marked?" The babies of all those to whom the question was submitted were normal; yet without exception those whose pregnancies just completed were their first answered in the affirmative. It is also pertinent that one of these patients had lost her brother by a violent and accidental death when she was four months pregnant; a similar bereavement was suffered by another at the eighth month; each was, however, delivered of a perfectly healthy child. Among those with whom the recently ended pregnancy was not the first I found some who could remember incidents popularly believed to have an influence over the development of the embryo; most of them, however, had given the matter so little thought that they could not definitely recall whether such incidents had occurred or not. From a similar series of observations covering two thousand cases, William Hunter came to the conclusion, nearly two hundred years ago, that there was no support for the belief in maternal impressions.
Whenever a child does happen to develop abnormally, it must be clear that, from the very nature of our existence, some incident can be recalled which will satisfactorily, yet unjustly, bear the blame. It may be confidently said, however, that, for every mother whose fears are realized, hundreds are agreeably disappointed in finding their babies perfectly normal. In the face of so many negative instances it is amazing that any person, even though ignorant of medical teaching, should be inclined to attribute abnormal development to something the mother has seen or heard, thought or dreamt, or otherwise experienced while she was pregnant. Yet unfortunately many do believe this. It is worth while, therefore, to supply further evidence, and thus escape any suspicion of unfairness in argument, to prove that maternal impressions are unable to affect the formation of the embryo.
It is found, as a matter of experience, that the superstition regarding maternal impressions generally begins to cause anxiety during the second half of pregnancy; and then such an influence is entirely out of the question. By the end of the second month the form of the embryo has been definitely determined, and subsequently cannot be altered. It is even true that errors in development are most apt to occur within the two or three weeks that immediately follow conception, and therefore occur at a time when pregnancy is not often clearly recognized. Thus it happens that women begin to worry about the influence their minds will have upon the formation of the child long after its form has been established.
Incidents in the life of a prospective mother are in point of fact equally inert so far as their influence upon development is concerned, no matter whether they occur during the earlier or later part of pregnancy. There is never any anatomical means by which maternal impressions could be conveyed to the embryo. Such an influence would have to be exerted through the placenta; and that is impossible. There are no nerves in the placenta to carry impulses from the mother to the child. Even the blood streams of the two beings are kept apart; and though it is unheard of that the blood should carry nerve impulses, if that happened to be the case, it could not prove effective here, for the blood of the mother does not enter the child. It is nourished by food which passes from the mother's blood, to be sure, but there is no more reason to expect this nutriment to exert an hereditary influence than there is to expect an infant to grow to resemble the cow with the milk of which it is fed. With these two possibilities eliminated, no path can be imagined by which impulses might travel from the mother to the embryo.
Scientific investigation has brought to light these facts, as it has also taught the real causation of the disfigurement once attributed to the mother's mind. Departures from the usual form of the body occur during the earliest days of pregnancy and arise in consequence of some irregularity in the process which molds the body-form from a simple spherical mass of cells. Why irregularities sometimes occur is not altogether clear; except in so far as it has been determined that the fault lies within the embryo itself. Whenever these defects are associated with events which have disturbed the mother's mind, it cannot be other than a simple coincidence.
CHAPTER IV
THE FOOD REQUIREMENTS DURING PREGNANCY
The Food-stuffs: Water; Mineral Material; Protein; Carbohydrate; Fat—
What We Do to Our Food—How Much Food Is Needed During Pregnancy?—
The Importance of Liquid Nourishment—The Choice of Food—Cravings—
The Relation Between the Mother's Diet and the Size of the Child.