The rate of maternal complications during pregnancy is relatively high. Pregnancy stresses maternal systems and these stresses can overwhelm homeostatic mechanisms. Preterm labour can occur spontaneously with unknown etiology. Causes of preterm labour are multiple pregnancy, cervical incompetence and uterine anomalies, premature rupture of membranes, maternal malnutrition or infection, chronic diseases, including hypertension, diabetes, kidney disease and hypothyroidism and smoking, alcohol use or misuse of other drugs.
Certain drugs can help to stop preterm labour: prostaglandin synthesis inhibitors, β-adrenoreceptor agonists, and Ca2+channel blockers. They act by reducing intracellular Ca2+levels or by increasing cAMP levels. They aim at reducing uterine contractility and thus postponing labour. Although the delay is only for hours or days, this extra time can be crucial for further development of the fetus and its survival.
During true labor, what physiological mechanisms ensure that uterine contractions continue until delivery has been completed?
Extra info: The hormonal process of delivery is a positive feedback of prostglandins and estrogens on oxytocin until the baby is born.