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

The purpose of this study was to determine the feasibility of infrared spectroscopy as an alternative method for the prediction of fetal lung development.

Samples of amniotic fluid were obtained by amniocentesis from 134 patients between the 26th and 41st week of pregnancy. To acquire infrared spectra with a commercial spectrometer, 35 microl of amniotic fluid was required for each spectrum. The lecithin/sphingomyelin ratio was determined separately by thin-layer 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.

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).

Infrared spectroscopy has the potential to become the clinical method of choice for determining fetal lung surfactant maturity in amniotic fluid.