Meconium

Meconium-stained fluid becomes more common with advancing gestational age and occurs in over 25% of pregnancies past 42 weeks. Meconium-stained amniotic fluid (MSAF) is due to a combination of increased fetal bowel motility and decreased clearance of meconium by the fetus or placenta. The use of meconium and sections of the umbilical cord appear to be equivalent for the evaluation of in utero exposure to drugs, alcohol, and environmental factors, and either may be used for this purpose. The diagnosis of MSAF is made clinically on the basis of appearance (i.e. greenish or brownish staining) or by histopathologic examination of the placenta. Symptoms of neonatal MAS include respiratory compromise, with tachypnea, cyanosis, and reduced pulmonary compliance. There is insufficient evidence to assess the effectiveness of antibiotics for women with meconium in labor. Toxicologic evaluation of meconium is regarded as the gold standard for assessment of in utero exposure to drugs and alcohol during pregnancy.