Rapid determination of fetal lung maturity from infrared spectra of amniotic fluid

Objective: The purpose of this study was to determine the feasibility of infrared spectroscopy as an alternative method for the prediction of fetal lung development. Study Design: Samples of amniotic fluid were obtained by amniocentesis from 134 patients between the 26th and 41 st week of pregnancy. To acquire infrared spectra with a commercial spectrometer, 35μl of amniotic fluid was required for each spectrum. The lecithin/sphingomyelin ratio was determined separately by thinlayer chromatography for each sample. A robust linear discriminant analysis method was used to partition the samples into normal and abnormal groups according to their infrared spectra. A partial least squares regression analysis was then applied to quantitatively correlate the infrared spectra with the thin-layer chromatography-based lecithin/sphingomyelin ratios. Results: Qualitatively, the infrared spectra of the amniotic fluid in the validation set were successfully partitioned into lecithin/sphingomyelin <2 and lecithin/sphingomyelin >2 groups. Quantitatively, the lecithin/sphingomyelin ratios predicted from the infrared spectra of amniotic fluid were highly correlated and in excellent agreement with those determined by thin-layer chromatography (correlation coefficient=0.893). Conclusion: Infrared spectroscopy has the potential to become the clinical method of choice for determining fetal lung surfactant maturity in amniotic fluid.