Lung development begins at approx 4 weeks gestation and continues throughout pregnancy
Testing for
Fetal Lung Maturity
Respiratory Distress
Syndrome
- Lamellar body count
- Lecithin/sphingomyelin (L/S) ratio
- Phosphatidylglycerol (PG)
- Most common cause of respiratory distress in preterm infant (most common in <38 weeks)
- Less surfactant produced by immature Type 2 pneumocytes leads to atelectasis and ischemia
Test for lung maturity 32-39 weeks gestation
Not necessary after 39 weeks (maturity likely) or before 32 weeks (immaturity likely)
Fetal Lung Maturity and Antenatal Steroids
Use of Antenatal Steroids
Accelerate development of Type 1 and Type 2 pneumocytes
Increased production of surfactant
by Type 2 pneumocytes
Improvement of lung mechanics and gas exchange!
Tiffany Chritz, OMS-IV
Recommended Treatment
Betamethasone (2 doses of 12 mg IM q24 hours) or
Dexamethasone (4 doses of 6 mg IM q12 hours)
When do you give steroids?
At 24-34 weeks gestation if increased risk of preterm delivery within the next 7 days
Should be considered routine for all preterm deliveries
References
- American College of Obstetrics and Gynecologists (ACOG) - ACOG Practice Advisory on Use of Antenatal Corticosteroids (2014), and Practice Bulletin Management of Preterm Labor (2012).
- Up To Date - Antenatal corticosteroid therapy for reduction of neonatal morbidity and mortality from preterm delivery (2015).