The measurement of amniotic fluid immunoglobulins by laser nephelometry.

Using laser nephelometry IgG, IgA, and IgM levels in amniotic fluid samples from normal pregnancies were measured between 15 and 24 weeks and between 37 and 41 weeks gestation. Not enough samples between 25 and 36 were available for statistical analysis. IgG levels increased until the 20th and 24th weeks of gestation and declined significantly at term. However amniotic fluid IgM and IgA levels rose at term. Five samples of amniotic fluid associated with a fetus of abnormal karyotype were examined. In one case of Down's syndrome excessive IgA and IgM levels were found. In amniotic fluid obtained after intrauterine fetal death at term, very high levels of all three immunoglobulins were found.