Salient. Victoria University Student Newspaper. Volume 39, Number 18, July 26, 1976.
Achievements of New Individual
Achievements of New Individual
First, and most pressing, he must prevent the menstrual shedding of the endomentrium. He does this by producing chorionic gonadotrophin to prolong the normally strictly limited life span of the corpus luteum, which in turn maintains the endometrium to undergo a decidual transformation.
This is a splendid feat of power amplification, understandable in electronic circuitry and very common in physiology, whereby an embryo barely out of the microgram range influences the corpus luteum in the milligram range, which in turn affects the endometrium measured in grams.
Very soon the embryo bypasses the corpus luteum and takes over direct control of the endometrium from a very early stage of human pregnancy neither the maternal pituitary nor ovaries necessary for its continued endocrine success.
In this regard the explanations in a dozen textbooks of witch's milk, of sebaceous retention cysts, of labial hypertrophy and withdrawal bleeding in the baby girl as the result of fetal exposure to high levels of maternal sex hormones are quite wrong.
It is the mother who is exposed to high levels of fetal hormones, for these hormones are manufactured by the fetus and his own placenta. These hormones are influential beyond mothers pelvis, for they modify maternal cardiovascular, respiratory and renal (kidney) function to cope with fetal requirements.
Another crucial environemental problem which must be dealt with is the homograft situation - the fact that the fetus and his mother, inevitably immunological foreigners, would not exchange skin grafts and could not be safely given a blood transfusion one from the other, yet must tolerate each other's tissues in parabiosis for nine months of pregnancy.
Again it is the fetus, not the mother, who copes with the problems. And finally it is the fetus, not mother, who determines the duration of pregnancy, for unquestionably the onset of labour is normally a unilateral decision by the baby.
This relationship between a baby and his mother is clearly simply much more than simple biological parasitism The term parasite, so frequently used to describe the fetus, is often used, not in the limited biological sense, but with the sociological overtone of describing someone who takes all and contributes no-thing. Neither sense is applicable to the fetus.
True, he is parasitic on mother for his nutritional requirements. In the same sense many wives could be said to be parasitic on their husbands' incomes; but just as wives would indignantly maintain that they contribute much to a home and a marriage to justify their keep, and that really is what is involved in a division of labour, so also does the fetus justify his keep by organising and maintaining the pregnancy.
Such a relationship is more accurately described as parabiosis or symbiosis (living together), and physiologically there is no question who guarantees its success.
This concept, that the fetus is in command of the pregnancy, is hardly news to any mother with an un-planned pregnancy, but the idea is new and the consequences are far-reaching in obstetrics. No longer can we understand the physiology of pregnancy if we re-main in ignorance of the physiology of the dominant partner in that relationship.
All the problems in pregnancy which can be solved by pulling and pushing and cutting have been solved the only unsolved problems, spontaneous miscarriage, premature labour, toxaemia and so on, await a better understanding of fetal physiology.
These achievements of the fetus also cause us to reconsider another point - the concept of maturity. It is perhaps one of the misfortunes of medicine that we study our subject as young adults, and our standards of normality are those of the young adult - usually male. And it is a part of the arrogance of young adults to consider that the only people who matter are young adults.