Meconium Stained Amniotic Fluid

The very first stool produced by a newborn infant is a dark green, sticky, tar-like substance called meconium. Meconium is made up of mucus, bile, epithelial cells, water, and other materials consumed by the infant during its time in the womb. Infants usually retain meconium in their bowels until after delivery, but occasionally it is passed in the uterus, resulting in meconium stained amniotic fluid. The staining can be light or heavy, and is considered hazardous for the fetus if it’s thick with dark green or black color. If inhaled by the fetus, the enzymes and bile salts in meconium can cause in a condition called meconium aspiration syndrome (MAS).

What Causes Meconium Aspiration Syndrome?

If the levels of oxygen in the womb are low, the fetus will experience stress and pass meconium in the uterus, causing meconium aspiration syndrome. Fetal stress is commonly a result ofone of the following conditions:

  • A pregnancy that goes beyond full term, in excess of 40 weeks
  • Extended and/or difficult, demanding labor
  • High blood pressure (hypertension) or diabetes in the mother
  • Infection

If a pregnancy goes beyond full term, the placenta, which delivers nourishment and sustenance to the fetus during gestation, can start to age; and an aging placenta does not provide enough oxygen in the womb. Additionally, an aging placenta decreases the volume of the amniotic fluid, subsequently concentrating the meconium. Thus, newborns who are past due are at a higher risk for MAS than premature or term babies.

How Would I Know if My Baby Has Meconium Aspiration Syndrome?

Signs and Symptoms

It is likely that your obstetrician will pick up indications of meconium aspiration syndrome before birth or during labor. Some signs and symptoms include:

  • Meconium stained amniotic fluid
  • The baby’s skin is discolored, either blue or green
  • Breathing complications such as tachypnea (hurried breathing), apnea (suspended or interrupted breathing), or difficulty breathing
  • The baby’s heart rate is low in the womb
  • The baby’s body feels limp or flaccid
  • The baby is exhibiting signs of post maturity, like long nails


Upon noticing meconium stained amniotic fluid, the healthcare team of nurses and physicians will evaluate the baby’s breathing and heart rate immediately after delivery, also performing an Apgar score test. Apgar stands for appearance, pulse, grimace, activity, and respiration. The Apgar score is a test performed on newborns usually at 1 minute and 5 minutes after birth, evaluating the baby’s condition. Breathing problems can be uncovered by this test.

High levels of carbon dioxide, low levels of oxygen, and low, acidic blood pH levels can be revealed by a blood gas analysis.

Additionally, complications in the baby’s lungs can be shown in a chest x-ray.

How Is Meconium Aspiration Syndrome Dealt With?

If a baby has developed meconium aspiration syndrome as a result of meconium stained amniotic fluid, he/she will need to be treated immediately after birth, as it is considered an emergency situation.The meconium is first removed from the upper airway by suctioning the mouth, throat, and nose. The doctor will then insert a tube in the newborn’s trachea, pulling out the meconium fluid, suctioning until there is no more meconium in the windpipe.

If the newborn is not breathing properly following suctioning, or the heart rate is low, the doctor will aid his/her breathing with a bag and mask, delivering oxygen to the baby’s lungs. It is possible for the newborn to require a breathing tube as well. Following emergency treatment, the baby’s breathing must be closely monitored.

Further treatments may be necessary to lower the risk of other complications of MAS. Typical treatments include antibiotic administration for infection, a ventilator for breathing assistance, oxygen therapy to ensure adequate blood oxygen levels, and using a radiant warmer to maintain the baby’s body temperature. If the newborn is unresponsive to treatment, or has high lung blood pressure, extracorporeal membrane oxygenation may be started to do the work of the baby’s heart and lungs.

How to Prevent Meconium Aspiration Syndrome

For an expectant mother whose water has broken, it is extremely important that you notify your doctor immediately if meconium or any dark green stains in the amniotic fluid are spotted.

Amnioinfusion may be used in certain instances. Amnioinfusion is the process by which the meconium stained amniotic fluid is diluted with saline, cleaning the meconium from the amniotic sac before birth, so the baby does not inhale it.

MAS can be a cause for fright, but most cases of it are fairly mild. Obstetricians closely monitor the fetus during pregnancy, looking for indications of meconium aspiration. Treatment can start right away if diagnosed. Early treatment is crucial for newborns diagnosed with meconium aspiration syndrome, and is the best way to prevent further complications.