Hyaline membrane disease (HMD), also called respiratory distress syndrome (RDS), is a condition that causes babies to need extra oxygen and help breathing.HMD is one of the most common problems seen in premature babies. The more premature the baby, the higher the risk and the more severe the HMD. HMD typically worsens over the first 48 to 72 hours and then improves with treatment. More than 90 percent of babies with HMD survive.

Ductus Arteriosus - The ductus arteriosus is a normal blood vessel that connects two major arteries - the aorta and the pulmonary artery — that carry blood away from the heart.

The lungs are not used while a fetus is in the womb because the baby gets oxygen directly from the mother’s placenta. The ductus arteriosus carries blood away from the lungs and sends it directly to the body. When a newborn breathes and begins to use the lungs, the ductus is no longer needed and usually closes by itself during the first 2 days after birth.

If the ductus doesn’t close, the result is a patent (meaning “open”) ductus arteriosus. The PDA lets oxygen-rich blood (blood high in oxygen) from the aorta mix with oxygen-poor blood (blood low in oxygen) in the pulmonary artery. As a result, too much blood flows into the lungs, which puts a strain on the heart and increases blood pressure in the pulmonary arteries. Sometimes, infants are born with certain heart problems that decrease blood flow from the heart to the lungs or decrease the flow of oxygen-rich blood to the body. In those cases, the PDA actually might help, and the doctor may prescribe medicine to ke