This opening allows blood to bypass the nonfunctional fetal lungs while the fetus obtains its oxygen from the placenta.

This delay is typically needed with corticosteroid treatment to help fetal lungs mature.

Labor needs to be delayed for 24 to 48 hours to: Let corticosteroids given to the mother help fetal lungs mature.

This compresses the fetal lung nearest the hernia, preventing full development, and thus interferes with breathing after the infant is born.

Starting in the 1970's, mothers got steroid injections to mature fetal lungs faster.

This receptor is normally present in fetal lungs, helping them to mature.

Learn whether fetal lungs are mature if the fetus needs to be delivered earlier than 37 weeks (preterm birth).

If fetal lungs appear to be mature, then delivery does not need to be delayed.

The drug, which is injected in the woman, crosses the placenta to the fetus, where it speeds maturation of the fetal lungs and blood vessels.

For the L/S ratio, if the result is less than 2:1, the fetal lungs may be surfactant deficient.