This is a decision you and your doctor will make. Although there are no studies on birth defects in humans, problems have not been reported. However, some studies in animals have shown that theophylline can cause birth defects when given in doses many times the human dose. Because your ability to clear theophylline from your body may decrease later in pregnancy, your doctor may want to take blood samples during your pregnancy to measure the amount of medicine in the blood. This will help your doctor decide whether the dose of this medicine should be changed.
Theophylline crosses the placenta.
Use of this medicine during pregnancy may cause unwanted effects, such as fast heartbeat, irritability, jitteriness, or vomiting, in the newborn infant if the amount of medicine in your blood is too high. Several groups of women taking guaifenesin during pregnancy have been studied. In one group, when guaifenesin was taken during the first 3 months of pregnancy, the babies had more inguinal hernias than expected. However, more birth defects than expected did not occur in the babies of other groups of women taking guaifenesin during pregnancy. Studies with guaifenesin have not been done in animals.