Congenital Pulmonary Airway Malformation (CPAM)
A small part of the baby's lung grew in an unusual way
CPAM is a group of small spaces, called cysts, in the lung. The spaces may be large or too small to see one by one.
CPAM is usually found in one part of one lung. That part does not work like normal lung tissue.
No one knows why CPAM happens.
Small CPAMs often cause no problem before birth. Some get smaller later in pregnancy.
What will be checked?
- Repeat ultrasounds check the CPAM's size and the baby's growth.
- A number called the Congenital Pulmonary Airway Malformation Volume Ratio (CVR) compares the CPAM's size with the baby's size. It helps show the chance of problems.
- The heart, other lung, and the rest of the baby's body are checked.
- An MRI or a special heart ultrasound may help in some cases.
Can CPAM cause problems?
A large CPAM can push the heart and press on healthy lung. Rarely, the baby can have swelling and fluid in two or more parts of the body. This is called hydrops and needs urgent care.
Your team will tell you how often you need an ultrasound.
Is treatment needed before birth?
Most babies with CPAM do not need treatment before birth. If the CPAM is very large or causes a serious condition called hydrops, your doctor may recommend steroid treatment. Steroids may help make the CPAM smaller and may improve hydrops. However, we do not yet know how well steroids work because only a small number of babies have been treated and studied. If early birth may happen, steroids may be given for a different reason: to help the baby's normal lungs get ready for birth. A large fluid-filled cyst may sometimes be drained or treated with a small tube.
What happens at birth?
- Your team will plan the safest place and time for birth.
- Many babies breathe well. Some need help breathing.
- CPAM alone does not always mean a C-section is needed.
Does CPAM raise chromosome risk?
CPAM alone is not known to raise the chance of Down syndrome or another chromosome condition. No CPAM type has proven higher risk. Type 2, confirmed after birth, is more often seen with problems in other parts of the body. The exact type often cannot be known before birth.
The ultrasound will check the baby's heart, kidneys, food tube, breathing muscle, and bones. If a problem is found in one of these areas, a genetics visit and amniocentesis may be offered. Amniocentesis uses a thin needle to take fluid from around the baby for chromosome testing. Testing is your choice.
What happens after birth and later?
Your baby will need a chest scan even if the CPAM became hard to see on ultrasound. A children's lung or surgery team will review it. Some babies need surgery. Others may be watched closely.
Most children can breathe, grow, play, and exercise normally. Healthy lung can grow and make up for lung removed by surgery. Some children have mild changes on breathing tests, wheezing, cough, or chest infections. Follow-up helps find and treat these problems.
Educational use only. This handout does not replace care from your pregnancy doctor or your baby's doctor. Your care plan may be different. Updated September 2026.
References
- The Fetal Medicine Foundation: Congenital pulmonary airway malformation
- Children's Hospital of Philadelphia: CPAM/CCAM
- UCSF Fetal Treatment Center: CPAM
- Cincinnati Children's Fetal Care Center: CPAM
- Hegde BN, Tsao K, Hirose S. Management of congenital lung malformations. Clin Perinatol. 2022;49:907-926.
- Unver G, et al. Congenital pulmonary airway malformations: prenatal markers, perinatal outcomes, and long-term follow-up experience. Rev Assoc Med Bras. 2026;72(6):e20260047. doi:10.1590/1806-9282.20260047.
- Sathian S, Pattanath D, Chullikkatil J. Antenatal diagnosis and management of congenital pulmonary airway malformation: a case report. Cureus. 2026;18:e102859. doi:10.7759/cureus.102859.
- Bina B, Bellussi F, Soni S, Berghella V. Maternal corticosteroids for fetal congenital pulmonary airway malformation: a systematic review. Am J Obstet Gynecol MFM. 2025;7:101763. doi:10.1016/j.ajogmf.2025.101763.
- Hijkoop A, et al. Lung function, exercise tolerance, and physical growth of children with congenital lung malformations at 8 years of age. Pediatr Pulmonol. 2019;54:1326-1334. doi:10.1002/ppul.24345.
- Nuutinen S, et al. Long-term results of pediatric congenital pulmonary malformation: a population-based matched case-control study with a mean 7-year follow-up. Children. 2023;10:71. doi:10.3390/children10010071.