What are fetal maturity tests?

Fetal maturity tests are diagnostic procedures to evaluate the readiness of the fetus for extrauterine survival. The pulmonary system is among the last of the fetal organ systems to mature, both functionally and structurally. Thus fetal lung maturation is a surrogate marker for maturity. An amniocentesis for fetal lung maturity can be performed if there is concern that the infant maybe at risk for immature pulmonary function.

A “cascade” testing model is recommended by the American College of Obstetricians and Gynecologists (2008). In this model, testing is continued until a mature result is achieved or all testing options have been exhausted. The sequence of the fetal lung maturity test cascade is:

  • Fluorescence polarization (surfactant/albumin ratio)
  • Lamellar body count
  • Phosphatidylglycerol presence
  • Lecithin-sphingomyelin ratio


Reference: ACOG Practice Bulletin No. 97: Fetal lung maturity. Obstet Gynecol. 2008; 112 (3) :717-726.PubMed

Fetal maturity tests are screenings performed on the amniotic fluid to determine the maturity of the fetus’ lungs, which indicates its ability to survive at delivery. This information is valuable when complications call for an early delivery or when the due date is uncertain. Babies born with immature lungs can suffer from respiratory-distress syndrome, or hyaline-membrane disease, which is the leading cause of death in newborns. This results from a lack of certain chemical substances that make it possible for the lungs to breathe oxygen.

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