In some cases the fetus is apparently not affected; in toxic cases it is affected, and then there may be miscarriage. If the fetus dies the vomiting ceases, as a rule. The liver enlarges in the first stage and later diminishes. There may be a general hemorrhagic hepatitis and acute yellow atrophy, or partial fatty degeneration around the central lobular veins. Necrosis also occurs. Acute parenchymatous nephritis and hemorrhages into the kidneys are often observed. Neurotic and hysteric women are more liable to this disease than the nervously stable. There is a direct communication by the sympathetic and vagus nerves between the stomach and the uterus and its adnexa, and thus reflex irritations readily pass to the stomach. Through this path vomiting is caused by any unusual distention of the uterus, as when the fetus grows too rapidly; or when the size of the ovum is larger than normal, as in twin pregnancies; or in irritations like hydramnios, displacement of the uterus, acute anteversions, retroversions, or flexions which pinch and stretch the nerves. Inflammations, as metritis, endrometritis, and cervicitis; tumors of the uterus; diseases of the adnexa or of the pelvic connective tissue or peritoneum are other sources of reflex vomiting. The proof that such are causes is that the vomit ceases when the conditions mentioned are cured. Such conditions exist, however, in women who are not pregnant without causing vomit; there is therefore some special disposition in the pregnant. Diseases which in themselves have vomiting as a symptom will in pregnancy make the vomit pernicious. Such are chronic gastritis, gastric ulcer, enteritis, cancer, helminthiasis, large fecal concretions, enteroptosis, tubercular peritonitis, and gall-stones. What is apparently pernicious vomiting in pregnancy may be the beginning of acute miliary tuberculosis. Diseases of the air passages--hypertrophied turbinates, septal spurs, laryngeal and apical tuberculosis--seem to cause the vomiting or to dispose to it. When vomit is associated with uremia, this occurs, as a rule, in the last months of pregnancy. The cause, again, may be in the nervous system, from either a demonstrable lesion or a functional imbalance--paresis, locomotor ataxia, tumors or tubercle of the brain, meningitis, polyneuritis. Even when the nervous system is not directly the cause of the emesis, the remote irritant may work through the nervous system. A bad neurotic inheritance, as from alcoholic, insane, or weak parents, disposes to neurotic hyperemesis.