In Sinclair Lewis' "Main Street," the best novel ever made about America as a nation of villagers, the heroine, Carol Kennicott, has this to say to someone sentimentalizing about maternity.
"I do not look lovely, Mrs. Bogar. My complexion is rotten, and my hair is coming out, and I look like a potato bag, and I think my arches are falling,… and the whole business is a confounded nuisance of a biological process."
The exploration of the internal secretions has brought us an explanation and an understanding of why child-bearing is a nuisance. We know now that if Carol Kennicott's complexion became rotten and her hair fell out, it was because her thyroid was not adequate to the demands of pregnancy, and that if her arches were falling, and her figure acquiring a potato bag dumpiness, it was because her pituitary was insufficient. In all probability she was a thymus-centered type, which accounts for much of the material that goes to make up the novel.
Different endocrine types react characteristically toward the situations of pregnancy. The adrenal type may not be able to respond with the necessary enlargement of its cortex which is normal for the needs of gestation. So pigmentations, darkenings and discolorations of the skin, especially of the face, the traditional chloasma develops. The hyperthyroid type may become sharply exaggerated, almost to the point of mania and psychosis. The subthyroid will suffer an emphasis of her defect, and pass on, because of pregnancy, to the truly diseased state of myxedema, the state of dull, slow, stupid, semi-animal semi-idiocy. The pituitary type becomes more masculinized. The face becomes more triangular and coarser, the chin and cheek-bones more pronounced, and there is a growth of all the bones, so that she is seen to grow visibly in height and breadth, and in the size of the hands and feet. Concomitantly, there is a changed, a more matured and steadier outlook upon life, all due to stimulation of the anterior pituitary, controller of growth, physical and mental.
In general, the major endocrines, the pituitary, the adrenals, and the thyroid should hypertrophy and hyperfunction during pregnancy. Should they not, should adverse mechanical circumstances or chemical malfunction prevent, dire effects may follow. A woman with the closed-in type of pituitary, shut up in a small non-expansile sella turcica, will suffer the most violent headaches, will become fat, will frequently abort. One whose thyroid cannot rise to the demands of gestation, because of previous disease (like typhoid or measles) which injured her thyroid excessively, may be poisoned by the new elements introduced into the blood by the growing fetus, as it is the job par excellence of the thyroid to render innocuous these poisons. Of adrenal insufficiency, failure of the adrenals to hypertrophy sufficiently in pregnancy, little is known. Possibly the corpus luteum, the endocrine formed of the torn egg nest in the ovary, makes up for any deficiency in this respect. For there is the most curious resemblance imaginable between the cells of the adrenal cortex and those of the corpus luteum, some day to be completely explained.
THE PLACENTAL GLAND
The placenta, an organ and gland of internal secretion newly formed in the uterus, when the fertilized ovum successfully imbeds itself within it, must be considered in any analysis of the transfigurations of child-bearing. Born with the pregnancy, its life is terminated with the pregnancy, for it is expelled in labor as the after-birth. Its importance and function as a gland of internal secretion has become known only recently. Many still doubt and question the accordance of that rank to it. But feeding experiments with it, in various endocrine disturbances in human beings, have proved its right to the title.
The placenta is created by the fusion of the topmost enlarged cells of the uterine surface and the most advanced cells constituting the vanguard of the growing and multiplying ovum. These front line invaders interact with the cells in contact with them to make a new organ which serves as lung, stomach and kidney for the embryo, since it is the medium of exchange of oxygen, foodstuffs and waste products between the blood of the mother and the blood of the embryo. Ultimately it acts, too, as a gland of internal secretion, influencing the internal secretions of the mother, and also those of the embryo.
Settlement of the fertilized ovum in the womb introduces into the system new secretions, new substances which are partly male in origin, since the ovum contains within it the substance of the male sperm which has penetrated it. This masculine element causes a rearrangement of the balance of power between the endocrines towards the side of masculinity. They push down the pan of the scale to inhibit the post-pituitary. So menstruation, the menstrual wave which follows the increasing tide of post-pituitary secretion, is postponed. For ten lunar months, not another ovum breaks through the covering of the ovary, and the uterus is left undisturbed. The placental secretion plays a most important rôle as brake upon the post-pituitary, the most active of the feminizing uterus-disturbing endocrines. Until at last something happens that puts the placenta out of commission in this function of restraint, and the long bottled up post-pituitary secretion explodes the crisis apparent as the process of labor.
A condition of self-poisoning often occurs in pregnancy, with symptoms orchestrating from mild notes like nausea and vomiting to the high keys of convulsions and insanities. They represent what happens when an unbalanced endocrine system is attacked by the placenta. Depending upon where in the internal secretion chain the weak point, the Achilles' heel spot, will be found, the nature of the reaction will vary. And even after labor, after the explosive crisis, so much of the reserve endocrine materials may be consumed, that an actual mania or a chronic weakness may come in its wake.