Amniotic fluid creatinine, uric acid and urea as indices of gestational age.

Abstract

Abstract. Amniotic fluid creatinine, uric acid and urea were measured by an automated method in 127 pregnancies. The concentration of each solute increased with gestational age. A creatinine concentration of 2.0 mg/100 ml could be used to pick up 52.9% of “mature” fetuses (i.e. fetuses which had passed the 37th week of gestation) but there was a false positive pick‐up of 5%. A uric acid concentration of 5.0 mg/100 ml correctly indicated a mature fetus in 41.5% of patients, the false positive pick‐up being 3.3%. Amniotic fluid urea was not a useful index of fetal maturity.