Chronic Lung Disease (CLD) in Premature Infants

Chronic lung disease (CLD) refers to long-lasting lung problems. In premature babies, chronic lung disease is caused by lung damage (bronchopulmonary dysplasia) that can happen when a baby is mechanically ventilated or given oxygen. Scarring and inflammation cause trouble breathing and oxygenating the blood, and the effects can last for months or years.

Premature baby with gloved hand rubbing its head
ERproductions Ltd / Blend Images / Getty Images

Difficulty breathing is the main symptom of chronic lung disease. Babies are considered to have CLD if they need respiratory support past the first 28 days of life, or after 36 weeks of gestational age.

Chronic lung disease may affect the rest of the body as well. Babies with CLD may have heart problems and trouble eating or gaining weight. Not all preemies who were on a ventilator will develop chronic lung disease. The chances of having chronic lung disease go up if a baby:

  • Was born before 30 weeks gestation
  • Weighed less than 3 lbs, 5 oz at birth
  • Had sepsis or an infection soon after birth
  • Is a boy or is white
  • Had a patent ductus arteriosus (PDA)

Most children will outgrow chronic lung disease by about age 2, as their bodies grow healthy lung tissue. Treatment is given to help with the symptoms of CLD as the lungs mature. Common treatments include respiratory support to make breathing easier, high-calorie nutrition to help growth, and medications to open up the lungs and reduce swelling and inflammation.

More Specific Definition of CLD

Chronic lung disease (CLD) is defined as respiratory issues that occur after 36 weeks post-conception. These respiratory problems can include respiratory symptoms (trouble breathing), need for supplemental oxygen and abnormalities exhibited on chest X-ray.

How Common CLD Is

CLD occurs in about 20% of infants born at 28 weeks. This disease is more common among those with lower birth weight, affecting nearly 80% of infants born at 22–24 weeks. Fortunately, few babies die of CLD. Nevertheless, CLD does result in reactive airway symptoms and recurrent infection, which can lead to multiple hospitalizations during the first two years of life.

Why CLD Happens

The reason why CLD happens in premature babies is that the lungs of these babies don’t properly mature and produce surfactant. Surfactant is a lipoprotein complex produced by alveolar cells, which reduces surface tension and helps us breathe.

Other factors contribute to the development of CLD in preterm infants, including exposure to chorioamnionitis, inflammation, high oxygen concentrations administered after birth and ventilatory trauma.


Advances in pulmonology critical care have helped prevent CLD in some preterm infants. These advances include early nasal CPAP (a type of mechanical ventilation) and surfactant-replacement therapy shortly after birth.


Here are some ways in which CLD is treated during the long term:

The administration of systemic (oral) steroids is controversial. Although systemic steroids may help decrease inflammation, which is a cardinal component of CPD, as well as help wean the baby off of mechanical ventilation, early use of dexamethasone (a type of systemic steroid) has been associated with increased risk of cerebral palsy. However, CPD itself can cause neurological impairment. Thus, the decision to administer systemic corticosteroids is complex and made by a pediatric pulmonologist.

5 Sources
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  2. Thébaud B, Goss KN, Laughon M, et al. Bronchopulmonary dysplasia. Nat Rev Dis Primers. 2019;5(1):78. doi:10.1038/s41572-019-0127-7

  3. National Organization for Rare Disorders. Bronchopulmonary dysplasia.

  4. National Heart, Lung, and Blood Institute. Bronchopulmonary dysplasia (BPD).

  5. Zayat N, Truffert P, Drumez E, et al. Systemic steroids in preventing bronchopulmonary dysplasia (BPD): neurodevelopmental outcome according to the risk of BPD in the EPICE cohort. Int J Environ Res Public Health. 2022;19(9):5600. doi:10.3390/ijerph19095600