[Parameters of fetal maturity in Rh-isoimmunization (author's transl)]

On 79 samples of amniotic fluid coming from 50 cases of Rh-isoimmunization submitted to amniocentesis one or more times, the following tests were done: a) creatinine; b) proteins; c) uric acid; d) urea; e) lecithin/sphingomyelin ratio. The results were related to the degree of immunization as determined by spectrophotometric curve of the amniotic fluid. For reasons of comparison, the same tests were performed on samples of amniotic fluid from 79 pregnant non-immunized patients. Determinations of creatinine, uric acid and lecithin/sphingomyelin ratio have pointed out a delayed fetal maturity in Rh-isoimmunized pregnant women, more marked in the more severe cases. The proteins level were increased, probably also because of the transfer of IgG antibodies into the amniotic fluid, whereas the estimation of fetal maturity based on urea concentrations is quite unreliable.