Fetal Lung Maturity: how fetal lungs mature

The last system of organs to mature in an unborn fetus is the fetal lungs, to prepare the baby on how to survive outside of the womb. This fetal lung development is structural and functional in nature. Fetal lung maturity is a very important aspect in growth and development of a fetus while it is still in its mother's womb. It is absolutely necessary for a fetus to have developed its lungs fully before it is born, as the baby must begin to breathe immediately. It is also important that the lungs are able to support the metabolic process of breathing where gases are exchanged in the lungs. This necessitates the full development of alveoli which numerous small sacs that make up the lungs.

Fetal Lung Maturity: three distinct events

The maturity of fetal lungs is normally completed when three distinct events have occurred.

  • The lungs must have enough surface are to allow gases to be exchanged within the lungs.
  • The lining of the small sacs that make up the lungs must be developed such that it comes into contact with the gases that are involved in the breathing process itself.
  • Finally, alveoli must be such that they are always open for the gaseous exchange to continuously take place. This is the general fetal lung maturity process.
the fetal lung maturity

The first two processes will be completed before the 34th week of pregnancy. The third process is slightly more complex as we will be explaining in the latter parts of this document.

The alveoli (little sacs) will want to collapse just like bubbles, due the external pressure that is exerted on them. To avoid this from happening, certain special cells must develop within their cellular walls to make them much stronger, so that they do not under the external pressure that is exerted on them. Special chemicals called ‘surfacants' are excreted in the cellular walls that do help in reducing their overall surface tension that are themselves a combination of apoproteins and phospholipids. This is a more complex explanation of what happens. Before this stage is completed, there is a risk that the unborn baby can develop a condition that is called RDS (Respiratory Distress Syndrome) but, this is a very rare condition and it occurs in less than one percent of all pregnancies. It usually necessitates labor to be induced before the expected delivery date.

Maturing fetal lungs practice breathing by taking in amniotic fluid that is mixed with some liquid discharge from the fetal lungs. Amniocentesis is the medical evaluation process used to check the fetal lung maturity though even after a diagnostic process; the obtained results do not guarantee that your child's growth will proceed as suggested by the indicated results. It is a non-invasive technique and it is carried out when there is a premature elation of the placental membrane.

Regular Checks

 fetal lung maturity

Before birth, it is very important to confirm that certain aspects involving fetal lung maturity are well known and documented. It is necessary that the fetal heartbeatis recorded after 30 weeks of pregnancy. After 36 weeks, it is absolutely necessary that tests for pregnancy by urine based test have come back as positive and a gestational age assessment has accurately determined the age of the unborn baby accurately after 39 weeks of labor. Another important thing to note is that due to the probable cases of an unborn baby's lung immaturity, predictive results at this stage of a pregnancy may not be accurately indicated or may be absent.

A fetal lung maturity test or assessment is not supposed to be carried out if delivery is going to be delayed. This is because this poses a significant amount of risk to the unborn baby and its mother as well. Research has also indicated that certain aspects of birth complications are associated with lung maturity. One example is that if the mother undergoes a C-section before the fetal lungs are fully developed, this significantly increases the chances that the baby will have respiratory problems particularly if this happens before the mother begins to experience labor.

Fetal lung maturity and premature delivery

When premature delivery is taking place, it is necessary to carry out a fetal lung maturity test. The most basic test is a lecithin-sphingomyelin test that measures the concentration ratio of the surfactants that are contained in the amniotic fluid and so this test therefore requires a sample of the amniotic fluid. A different test tries to detect the presence of phosphatidylglycerol in the amniotic fluid. This substance plays a major role in in spreading phospholipids in the alveoli and it is normally present if fetal lung maturity has reached advanced stages in the overall development of the unborn baby. Fetal lung maturity is therefore on of the most important aspects in the growth and development of an unborn baby before birth.

the fetal lungs