In most cases the fetus will do well and be carried to term without a problem. The mass may grow in the chest to very large size between 20th and 30th week of pregnancy. During that time, the fetus will have rapid growth and the mass may appear smaller or unchanged. The CCAM may also shrink and even disappear during the third trimester of pregnancy. However, in a small number of cases, the mass may grow to be life threatening to the fetus. As it grows, there is potential for it to cause shift of the heart, compression of the blood vessels causing the heart to pump harder to circulate the blood, possibly leading to heart failure (hydrops).

Doctors will be paying close attention to the mother's health status. As the fetus develops hydrops, the mother can mirror the signs and symptoms with preeclampsia (high blood pressure and protein in the urine.) If the hydrops gets too severe and the mother is very ill, doctors may not be able to perform surgery.

If hydrops is imminent or the fetus develops hydrops and it isn't too severe, prenatal intervention will be offered sometime prior to 28 weeks gestation. The procedure involved depends on the type of CCAM. If the mass is cystic in appearance, then it usually can be drained percutaneously (with a needle and a drain). If the fluid reaccumulates, a shunt can be placed to continuously drain the cyst.

Sometimes the mass needs to be removed during open fetal surgery, when it is solid and sometimes even when it is cystic. This procedure usually occurs prior to 28 weeks of pregnancy. In this case, the mother is placed under general anesthesia, the uterus is surgically opened, the fetus is partially taken out of the uterus and the mass is removed. The fetus is returned to the uterus, which is then closed, and the mother and fetus are monitored closely after the procedure. There is a risk for preterm labor when an incision is made in the uterus, but medications are given to help control the contractions. For more information, see Fetal Surgery.

Oftentimes babies will have no symptoms after birth. In that case, an x-ray will be performed and the baby will go home with mother. At around 3 months of age, the baby will undergo a special x-ray called a CT Scan, which gives health professionals a three-dimensional image of the lung and the growth.

Surgery to remove the CCAM will be scheduled during the baby's first 3-6 months of life. The hospital stay is usually about 3-5 days. The pediatric surgeon will continue to see the baby after he is discharged from the hospital. Babies who have the CCAM removed either before or after birth can usually expect to do well afterwards. Lungs continue to grow until the child is 9 years old, leaving plenty of time for the development of normal healthy lungs.