Significance of meconium in midtrimester diagnostic amniocentesis.

The importance of meconium passage as a sign of the third-trimester fetus in distress is well known. The significance of similar observations in the midtrimester fetus is much less certain. The increasing use of amniocentesis during the middle trimester for the diagnosis of genetic disease makes ascertainment of such data important. Ten instances of meconium-stained amniotic fluid in the last 514 amniocenteses performed at our institution for antenatal genetic diagnosis are reported. Seven pregnancies have ended at term with normal deliveries. Three pregnancies have terminated with fetal death. Meconium staining may be a sign of impending fetal death when passed during the second trimester. When accompanied by alpha-fetoprotein elevation two of three pregnancies terminated with fetal death.