According to Drs. Guoyang Luo, and Errol R Norwitz, the lungs are among the last of the fetal organs to mature. These authors state in a study published in 2008 in the journal "Reviews in Obstetrics and Gynecology" that immature lungs are a major cause of death among preterm infants. That is why the maturity of the lungs should be tested before preterm delivery. Several tests are available to sign the maturity of the lungs if the fetus. After the birth of the baby, one important sign of the lung maturity is that the baby does not develop respiratory distress syndrome, or RDS. His brains also get enough oxygen and the baby develops normally.
Lung Maturity Tests
A clear sign of lung maturity in fetuses is that all the lung maturity tests come back as positive. According to Dr. Ashraf Fawzy Nabhan at the ObGyn.net, the main methods to test for the lung maturity in fetuses include quantitation of pulmonary surfactant, measurement of surfactant function, evaluation of amniotic fluid turbidity, and ultrasonography. Out of these the quantitation of pulmonary surfactant is the most commonly used. The first three tests are taken from the amniotic fluid. Ultrasound studies can be used to verify the gestational age. They are not used alone to determine the lung maturity.
Lung Functions
According to the MedlinePlus.com, in mature lungs, there must be large enough surface area in the lung for the exchange of oxygen and carbon dioxide to happen. Millions of small sacs called alveoli allow this. The inner lining of cells that come in contact with air must be thin to allow the oxygen and carbon dioxide exchange. The alveoli must also be able to remain open. Unfortunately, it takes quite long for the lungs to reach the maturity stage where they alveoli can remain open. It is common for the immature alveoli to collapse. To prevent this from happening, the type II alveolar cells begin to excrete chemical called surfactant that reduces the surface tension in the alveoli. The production of this chemical that allows the alveoli to remain open is a clear sign that the lungs are mature.
Newborn Breathing and Appearance
According to the MedlinePlus.com it becomes quite clear within minutes after the baby has been born whether his lungs are mature. The skin color of an infant that does not receive enough oxygen is bluish. A newborn with mature lung function breaths normally. Breathing is not rapid, or shallow, and there is no signs or apnea, or brief stops in breathing. The arms and legs of the infant appear normal. Puffy and swollen arms or legs are a sign of lung immaturity. Urine output is normal; decreased urine output is another sign of lung immaturity.
References
- "Reviews in Obstetrics and Gynecology Journal"; Revisiting Amniocentesis for Fetal Lung Maturity After 36 Weeks' Gestation; Guoyang Luo, MD, PhD and Errol R Norwitz; Spring 2008
- ObGyn.net: Assessment of Fetal Lung Maturity; Dr. Ashraf Fawzy Nabhan; August 2010
- MedlinePlus.com: Neonatal respiratory distress syndrome
