What L/S ratio confirms lung maturity?

L/S ratio ≥2.0 indicates pulmonary maturity. In diabetic pregnancies, higher threshold (≥3.0) is used as L/S may be elevated despite functional immaturity. PG present = mature, regardless of L/S ratio.

Is L/S ratio still used clinically?

L/S ratio has largely been replaced by faster tests (TDx-FLM, lamellar body count) in most centers. LBC (lamellar body count) ≥50,000/μL correlates with mature L/S ratio and is available on standard cell counters.

When is fetal lung maturity testing indicated?

When delivery at 34 0/7 to 38 6/7 weeks is planned without standard obstetric indication, fetal lung maturity documentation may guide decision. ACOG generally recommends against routine lung maturity testing before 39 weeks elective delivery.

Fetal Lung Maturity L/S Ratio and Phosphatidylglycerol

Calculate fetal lung maturity from lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) status in amniotic fluid. L/S ≥2.0 and PG present indicates maturity with <1% risk of RDS in term infants.

Use the full interactive calculator below, or

Related Calculators

Antenatal Corticosteroids

Hyper-niche Medical

Fetal Lung Maturity L/S Ratio and Phosphatidylglycerol

Related Calculators

Frequently Asked Questions

What L/S ratio confirms lung maturity?

Is L/S ratio still used clinically?

When is fetal lung maturity testing indicated?