Laboratory assessment of fetal lung maturity assists obstetricians in estimating the risk of respiratory distress syndrome (RDS) when premature delivery of an infant is being considered. The status of fetal lung maturity is reflected in the concentrations of specific phospholipids and the number of surfactant-containing particles, or lamellar bodies, in amniotic fluid. Since lamellar body volumes are similar to platelets, automated hematology analyzers can provide rapid and precise lamellar body counts (LBCs). However, hematology analyzer manufacturers use different methods to enumerate platelets, leading to a lack of concordance between instrument brands when counting lamellar bodies. Laboratories performing LBCs should be aware of this important analytical variable when providing interpretations of LBC results.