- Health Topics
- Health Education
- The Science
- Grants and Training
- News and Events
- About NHLBI
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
RDS is a type of neonatal respiratory disease that is caused most often by a lack of surfactant in the lungs. A fetus's lungs start making surfactant during the third trimester of pregnancy, or weeks 26 through labor and delivery. Surfactant coats the insides of the air sacs, or alveoli, in the lungs. This helps keep the lungs open so breathing can occur after birth. To understand respiratory distress syndrome, it helps to learn about how the lungs work.
Without enough surfactant, the lungs may collapse when the newborn exhales. The newborn then has to work harder to breathe. He or she might not be able to get enough oxygen to support the body's organs.
Some full-term newborns develop RDS because they have faulty genes that affect how their bodies make surfactant.