<prompt> Liley curve for evaluation of amnionic fluid bilirubin in Rh sensitized patient stas at14weeks16weeks20weeks26weeks  <response>: The main limitation of the liley curve is that it stas at 26weeks gestation and extrapolation of the lines to earlier gestational ages is inaccurate. Queenan has developed a curve for fetal assessment from 14-40weeks, divided into 4zones 