Respiratory complications in the late-preterm (LPT) newborn

During development of the respiratory system, the lungs begin production of a substance called surfactant at 32-33 weeks gestation.  Neonates that are born at or before this time are at a significantly higher risk for respiratory distress because of the absence of surfactant.  This lubricant is responsible for providing the elasticity of the lungs.  Maximum levels of surfactant are reached between 38-40 weeks gestation Engle, Tomashek, & Wallman, 2007).  Morbidity related to respiratory distress syndrome (RDS) has decreased significantly since the introduction of manufactured surfactant, such as Survanta® in 1991.  http://abbottnutrition.com/Products/Survanta.aspx
 Other issues that contribute to respiratory problems in the LPT newborn are related to gas exchange that is less effective than that of a more mature newborn.  Alveoli are lined with epithelial cells that thin with maturity improving gas exchange and fluid absorption; the last few weeks of pregnancy.  Transient tachypnea of the newborn (TTN) is seen more often in the LPT newborn especially if delivered by C section.  For 6-24 hours, occasionally longer, the newborn is breathing at rates of 80-100/minute due to this increase in retained fluid (Bakewell-Sachs, 2007).
Apnea is a complication in 4-7% of LPT newborns.  Besides causing anxiety in the parents, this can lead to bradycardia and ultimately hypoxia.  Some reasons for this apnea include poor sensitivity to stimulation of the larynx and poor response to an increase in carbon dioxide levels due to a decrease in the sensitivity to the gas while there is an increase in the response to irritants.  Poor muscle tone in the upper airway and central nervous system immaturity also play a role (Engle, Tomashek, & Wallman, 2007).
 Environments where the newborn is exposed to smoking increased the respiratory problems for these newborns.  This includes contact with clothing worn in the presence of smokers.  Third hand smoke is causing more than just respiratory problems in these newborns; it is also dangerous to their more sensitive brain .  Read more in this article. http://www.scientificamerican.com/article.cfm?id=what-is-third-hand-smoke
Every day that the fetus remains in the uterus improves lung maturity and decreases the risks for prolonged hospitalization and long term respiratory problems.  Morbidity related to respiratory complications has been reported to be between 4 and 29% (Engle, Tomashek, & Wallman, 2007).

References

Bakewell-Sachs, S. (2007, June). Near-term/late preterm infants. Newborn & Infant Nursing Reviews, 7(2), 67-71. doi:10.1053/j.nainr.2007.05.001

Ballantyne, C. (2009, January 6). What is third-hand smoke? Is it hazardous? Researchers warn cigarette dangers may be even more far-reaching. Scientific American. Retrieved from http://www.scientificamerican.com/article.cfm?id=what-is-third-hand-smoke

Engle, W. A., Tomashek, K. M., & Wallman, C. (2007). “Late-preterm” infants: A population at risk. Pediatrics, 120(6), 1390-1401. doi:10.1542/peds.2007-2952