With regard to mental defects, as a rule, not so much is said as for bodily defects. Bodily deformities are noted at once after birth, and then the mother recalls some incident of the pregnancy to account for them. Mental defects are, however, noticed much later, and are not so likely to be considered as connected with incidents of the puerperal period. There is no doubt that if the mother has had to pass through a series of emotional strains, or has suffered from severe [{64}] shocks, children are likely to be born with diminished mental capacity. This is, however, not difficult to understand, since such incidents produce disturbances of the nervous system of the mother, and consequently also of her nutrition, and this is prone to be reflected in the child's condition, especially in that most delicate part of the child's organism, the brain. Hence it is that children born during the siege of Paris, or shortly after, were defective to such a marked degree that they were spoken of as "children of the siege," and this was considered to be quite sufficient explanation of nervous peculiarities later in life.
Baron Larrey, the distinguished French surgeon, made a report with regard to the children born after the siege of Landau in 1793. Of 92 children, 16 died at birth, 33 died within ten months, 8 showed marked signs of mental defects, most of them to the extent of idiocy, and two were born with several broken bones. In this case, however, it is well known that besides the shock of the danger consequent to the siege and the fear and distress of the women with regard to their husbands and relatives, there were added many privations and physical sufferings. The nutrition of the mothers was seriously disturbed by these, and it might well be expected that the children should suffer severely. The statistics of such events are not available in general, and when an effort is made to establish a cause for idiocy under other circumstances, none is usually found. Out of nearly five hundred cases of idiots whose histories were carefully traced in Scotland, in only six was there any question of maternal impressions having been the cause of the condition.
Of course there are many very wonderful coincidences that seem to confirm the idea that impressions made upon the mother's mind are sometimes communicated to the child in her womb. That they are not more than coincidences, however, is rather easy to demonstrate in most cases, since, as a matter of fact, at the time when the incident occurred which is supposed to have caused the deformity in the foetus, the stage of development of the intrauterine child has passed long beyond the period when formative defects could occur. For instance, it sometimes happens that the child-bearing woman [{65}] sees an accident especially to the father of the child involving the loss of a limb. If, by chance the child should be born with a missing member, as sometimes happens, then there would seem almost to be no doubt of a direct connection between the accident witnessed, the effect produced upon the mother's mind, and the consequent deformity.
We know now that the formation of the limbs of the foetus is complete by the end of the third month. At this time the woman is scarcely more than conscious of the fact that she is pregnant, and it is not during this early period, as a rule, but during a much later period, that maternal impressions are supposed to have their influence. It is only such maternal impressions as occur very early in pregnancy, before the tenth week as a rule, that could possibly have any effect in the production of such deformities. It is by no means infrequent, however, to have children born lacking one or both limbs. Sometimes nothing but the stumps of limbs remain. In such cases it is now well known that intrauterine amputation has taken place. Some of the membranes that surround the child, especially the amnion, become separated into bands which surround tightly the growing members of the foetus and by shutting off the blood supply through constant pressure, lead to the dropping off of all that portion of the member lying below the band.
Not infrequently it happens that when a child is born thus deformed, the mother, by carefully searching her memory, can find some dreadful story that she has read, some accident that she has seen or heard of, and that has produced a seriously depressing effect upon her at the time, to which she now attributes the deformity that has occurred. Until the unfortunate appearance of her child was reported to her, she had no idea of any possible connection between the story and the bodily state of her intrauterine child. In not a few cases, however, the most faithful searching of the memory fails to show anything which could, by any possible connection, be made accountable for the deformity; and these cases, we may say at once, are in a majority.
Not a little of a popular notion with regard to the influence of maternal impression is due to the repetition of certain [{66}] village gossip which by no means loses its point or effectiveness passing from mouth to mouth. On the other hand, maternal impressions have been exploited by novelists, who have found that the morbid curiosity of women particularly with regard to this subject may make their stories more widely read. Lucas Malet, who, in spite of the apparently masculine pseudonym, is really the late Rev. Charles Kingsley's daughter, has recently called renewed attention to this subject by her novel "Sir Richard Calmady." In this the hero is born with both his lower limbs missing from just below the knees. The author has been careful, however, with regard to the details of the supposed maternal impression to which this deformity is attributed. A young married woman in the early part of her first pregnancy has her husband, whom she loves very dearly, brought back to her with both his limbs taken off by a shocking accident which resulted fatally. It is not impossible, some physicians might think, to consider that so severe a shock could produce a very deleterious effect upon the foetus. That the result should so exactly copy the scene which was brought under the eyes of the young mother is, however, beyond credence. Occasionally such stories, supposedly on medical authority, find their way into the newspapers, usually from distant parts of the country. Certain parts of Texas particularly seem to be a fruitful source of such stories for newspaper correspondents when there is a dearth of other news. Farmers in thinly settled parts of the country lose a foot in a reaping machine or a hand in the hay-cutting machine when there is no one near to help them but their wives, with the result that the shock to their wives proves the occasion of a similar deformity in an as yet unborn child. Careful investigation of such cases, however, has invariably shown that either they were completely false or that the details showed that whatever had happened was at most a coincidence and never a direct causative factor in the subsequent deformity.
The greatest difficulty in the mind of the medical man, with regard to the possibility of maternal impression being communicated in any way to the foetus, is, as we have said, his knowledge of the anatomy of mother and foetus. While it is [{67}] generally supposed that the mother is very intimately connected with her child in utero, the actual connection is by no means so direct as might be expected from the popular impression. It is usually considered that the mother's blood flows in the child's veins; but this is absolutely false. The child's blood is formed independently of the mother's blood quite as is that of the chick in the egg. At all times the blood of the child remains quite different in constitution to that of its mother. It contains many more red cells than does her blood and differs in other very easily recognisable ways. Mother and child are connected by means of an organ known as the placenta, which is attached very closely to the uterine wall and from which through the cord the blood of the foetus circulates. This placenta constitutes the so-called afterbirth. The mother's blood flows in one portion of it, that of the child in another, and they always remain distinct and separate from each other. The gases necessary for the child's life diffuse through the membrane which separates the two different bloods, and the salts and soluble proteids necessary for the child's nutrition, as well as the water necessary for its vital processes, all pass through this membrane, but at no time is there any direct blood connection between mother and child. Indeed, for a large part of the formative period of the foetus life, that is, during the first two months of its existence, the ovum is not very closely attached to the uterus at all, but grows by means of the vital power which it has within itself.
Nor is there any direct nervous connection between mother and child; indeed, there are no nerves at all in the placenta, and none in the cord through which all communications between mother and child must pass. It seems impossible to explain, then, how maternal impressions can so effectively pass from mother to child; and indeed, the whole subject, when looked at in this way, is apt to be considered legendary, and the facts adduced in support of the theory of maternal impressions are practically sure to be thought mere coincidences. A little knowledge here might seem to justify many things that more complete knowledge fails to be able to find any reasons for.
There is no doubt, however, that the mother's environment during pregnancy is in general very important for the perfect development of the intrauterine child. Many more deformed births are reported after times of stress and trial, as, for example, after the sieges of great cities, notably the siege of Paris in 1871, and such scenes of desolation as occurred during the thirty years' war in Germany. These are, however, not direct, but indirect effects of maternal impressions. The development of the human being in utero is an extremely complicated process. Any disturbance of it, however slight, is sure to be followed by serious consequences. Disturbances of nutrition, such as are consequent upon the deprivation that has to be endured in times of war or during sieges, is of itself sufficient seriously to disturb even the uterine life of the child. In these cases, however, there will be no traceable connection between the form of the maternal impression and the type of deformity that occurs. This is, however, the essence of the old theory of the direct effect of maternal impressions, and consequently that theory must fall to the ground.