Definition
Meconium is the first feces (stool) of the newborn. It is thick, sticky, and greenish-black in color and may be seen in the amniotic fluid after 34 weeks gestation. Aspiration occurs when the newborn inhales the meconium mixed with amniotic fluid either in the uterus or just after delivery. MAS occurs when a newborn inhales (aspirates) a mixture of meconium (baby's first feces, ordinarily passed after birth) and amniotic fluid during labor and delivery. Although meconium is passed in up to 20% of births, not all infants who pass meconium develop MAS. Of the babies who pass meconium, 20% to 30% either inhale the meconium in utero or with the first breath. (Glantz, 2002)
The inhaled meconium can cause a partial or complete blockage of the baby's airways. Air flows past the meconium trapped in the baby's airways as she breathes in; however, it becomes trapped in her airways when she exhales. In addition, the inhaled meconium irritates the baby's airways and makes it difficult for her to breathe.
The severity of MAS depends on the amount of meconium the baby aspirates. Generally, the more meconium a baby inhales, the more severe the condition. The consistency of meconium also affects your baby's condition. Infants who pass thin meconium, which is yellow to light green and watery, are more likely to be healthy at birth. They are at lower risk for MAS than babies who pass thick meconium, which is pasty or granular and can be a variety of colors including dark brown or black.
For this reason, babies known in advance or discovered at delivery to have meconium staining of the amniotic fluid, especially if the meconium is chunky and particulate, will usually be suctioned out as quickly as possible after birth before the first breath is taken is best..................
