Meconium is a thick, green, tar like substance that lines your baby's intestines during pregnancy. Typically this substance is not released in your baby's bowel movements until after birth. However, occasionally you will find that your baby will have a bowel movement prior to birth, excreting the meconium into the amniotic fluid.
If meconium is present during your labor and birth, you will be watched more closely for signs of fetal distress. Alone, meconium staining of the amniotic fluid does not mean that your baby is suffering from fetal distress. However, since it is one sign, your labor and birth team will look for others.
Meconium that is light is not as much of a risk to your baby, nor is it as likely to be a sign of fetal distress, but rather the maturation of your baby. There are thicker quantities of meconium that can also be present, including one level that is so thick they refer to it as pea soup, both in consistency and because of the greenish shade of meconium. This is more of a danger to your baby.
If there is meconium present in labor, in addition to watching for signs of fetal distress, like more intense monitoring, your doctor or midwife may also decide to do an amnioinfusion.
Amnioinfusion is where sterile fluid is placed inside the uterus via a catheter to help dilute the meconium. It also can be used to add to the amniotic fluid volume. This could be done more than one time if needed and may increase your baby's tolerance of labor. If your baby is still not tolerating labor well or shows other signs of fetal distress that aggressive therapy has not corrected, your doctor or midwife may decide that you need to discuss an operative delivery depending on how far away you are from a vaginal delivery. This may include forceps, vacuum extraction or a cesarean section.
Meconium is more common if you are well past your due date. One of the concerns when there is meconium present in the amniotic fluid is that the baby will aspirate the meconium during the labor or birth. This aspiration of meconium is dealt with by vigorous suctioning immediately upon the birth of your baby's head, even before the body is born. This can lessen the amount of meconium available for your baby to aspirate.
Meconium can be not only swallowed, which is not usually a problem, or it can be inhaled into the lungs of your baby. This can cause a problem, it is called Meconium Aspiration Syndrome. Meconium being a thick, sticky substance can cause problems for your baby in inflating the lungs immediately after birth. It can also lead to meconium aspiration pneumonia. These both can be very serious problems resulting in a stay in the neonatal intensive care unit (NICU) for your baby for treatment consisting of several days to weeks depending on the severity of the problem.
If your baby does not have meconium prior to birth, you will still see it within the first few days of life. This is not a problem. However, it's messy and hard to clean of your baby's bottom. A great hint for making newborn diaper changes easier, you simply coat your baby's bottom with some ointment or even oil after washing up during diaper changes. This prevents the meconium from sticking!
See also: New Baby Diaper Decoder