The most frequent causes are the chronic infections. Chronic nephritis is one of the most frequent causes of spontaneous premature labor, and the offspring of these mothers are often puny, due, either to the systemic affect on the mother, or resulting from impaired nutrition of the fetus due to placental hemorrhages and infarcts. Nephritis in the mother is also one of the most frequent indications for the induction of premature labor. Pulmonary tuberculosis is less frequently the cause of premature labor, but the children, even at full-term, are often small and weak. Tuberculosis of other organs and tissues influences the fetus in proportion to the nutritional effect upon the mother or, again when involving the vertebral column or hip-joints may by their resulting deformities require premature induction of labor.
Congenital tuberculosis is very rare, but does occur.
In the majority of cases, not the disease per se , but the predisposition is inherited. Premature birth occurs in 30 or 35 per cent of the cases of broken compensation in heart disease . The premature infants are, in these cases, often imperfectly nourished as a result of the poor aeration of the mother's blood. Exophthalmic goiter is occasionally the cause of premature emptying of the uterus. If chronic dyspnea exists, as a result of laryngeal or tracheal stenosis from pressure, the development of the fetus will necessarily be retarded.