Assessment of fetal lung maturity by fluorescence polarization in high-risk pregnancies.

Although the validity of amniotic fluid fluorescence polarization (FPOL) has been documented in normal pregnancies, data are lacking on the predictive value of this method in high-risk pregnancies where biochemical maturation of the fetal lung may be altered. In this study, amniotic fluid was obtained from 86 women with pregnancies complicated by insulin-dependent diabetes (42), twin gestation (22), Rh sensitization (13) and known fetal anomalies (9). In all groups, when FPOL was > .280 (immature), phosphatidylglycerol (PG) was always absent and lecithin and sphingomyelin ratio (L/S) was < 2.5:1. When FPOL values were < .260 (mature), PG was always present and L/S was > 2.5 in 45/50 samples. When FPOL values ranged between .260-.280 (intermediate), L/S and PG values varied and were inconsistent. We conclude that FPOL assessment of fetal lung maturity in pregnancies complicated by diabetes, Rh sensitization, twin gestation and fetal anomalies is as accurate a procedure as is fetal lung maturity testing by L/S and PG. In addition, the testing procedure is quicker, more reproducible and, possibly, more reliable.