The key to a successful pregnancy for asthma sufferers is symptom management. Maternal asthma that is adequately controlled during pregnancy does not increase the risk of maternal or infant complications. Uncontrolled asthma causes a decrease in the oxygen in the mother's blood. Since the fetus gets oxygen from the mother's blood, asthma can lead to fetal blood oxygen. Normal growth and development require a constant supply of oxygen, which again underscores the need to manage the symptoms.
Studies indicate a correlation between uncontrolled asthma and babies with a lower birth weight.
In rare cases, the extremely hard coughing that accompanies an attack can cause premature labor, or can cause the placenta to separate from the uterus. The goal of asthma therapy during pregnancy is virtually the same as in non-pregnant patients. The goal is to prevent hospitalization and emergency room visits as well as lost time at work and chronic disability. Avoidance of allergens and irritants including exposure to pets and the harmful effects of cigarette smoke becomes especially important in controlling asthma. Alcohol should be doubly avoided by the pregnant woman with asthma, because it can harm the developing fetus and because it can cause bronchial constriction as it is exhaled through the lungs.