Amniotic fluid bilirubin

Bilirubin in amniotic fluid is produced by the destruction of fetal red blood cells. The way to enter the amniotic fluid may be through the lungs or skin, mostly unbound bilirubin, and the bilirubin content in amniotic fluid is high during early pregnancy. As the fetal liver function gradually matures and improves, the bound bilirubin in the fetus gradually increases, and the unbound bilirubin in the amniotic fluid gradually decreases, and the concentration is extremely low, or even 0, in the third and final stages of pregnancy. Because the content is too small, it is not easy to detect by ordinary chemical methods, and the absorbance difference needs to be determined.