Meconium Aspiration Syndrome

Meconium aspiration syndrome occurs when an infant breathes in meconium and amniotic fluid before or during birth.

Meconium aspiration syndrome (MAS) is a serious, life-threatening condition that occurs in around two to five percent of all births. Although the mortality rates of infants with MAS have vastly improved over the past few decades, infants are still at a heightened risk of lifelong medical complications, especially if medical treatment doesn’t start immediately.

meconium aspiration syndrome

What is Meconium Aspiration Syndrome?

MAS is a medical condition that occurs when an infant breathes in a mixture of meconium and amniotic fluid. Meconium is, essentially, the infant’s first bowel movement. It is dark, thick and sticky, and is composed of proteins, fat and cells. Generally, infants pass meconium a few days after birth. However, with MAS, the infant passes meconium while still in the womb, which can cause them to breathe it in. This mixture floods the lungs at the time of delivery, and may cause oxygen deprivation.

What Causes Meconium Aspiration Syndrome?

While the mother is still pregnant, the fetus may feel stressed out if there are placenta issues. If this occurs, the infant may defecate and in turn breathe in meconium while still in the uterus. The baby is also likely to breathe it in during delivery, which may block the infant’s airways just after delivery.

Risk factors that may contribute to fetal stress include:

  • Maternal diabetes
  • Maternal high blood pressure
  • A placenta that ages past the infant’s due date
  • Lack of sufficient oxygen to the infant while in utero
  • Intrauterine growth restriction (IUGR)
  • Postdates pregnancy

What are the Symptoms of Meconium Aspiration Syndrome?

One of the most obvious symptoms of MAS is a bluish appearance shortly after birth. In addition, babies may experience:

  • Lack of breathing, rapid breathing, or no breathing at all
  • Limpness
  • Slow heart rate shortly before birth
  • Low Apgar score

How Can Meconium Aspiration Syndrome Be Treated?

If an infant comes out breathing and crying normally, no treatment is usually necessary. But if there are crackling noises while breathing and lack of activity shortly after delivery,  physicians generally insert a tube into the infant’s airways to clear out the meconium and amniotic fluid.

If the baby isn’t breathing, a face mask is usually used to deliver oxygen and inflate the lungs.

Additional treatments may include antibiotics to treat infections, a radiant warmer to help keep body temperature normal, and a ventilator to keep the infant’s lungs from collapsing.

How is Meconium Aspiration Syndrome a Birth Injury?

One way of preventing MAS is for the doctor to monitor the baby’s health and the health of the placenta before delivery. If the baby is born with what appears to be MAS, it is the responsibility of the medical professionals to get the infant immediate medical treatment. If left without oxygen for too long, the baby’s brain can experience oxygen deprivation that can cause additional complications such as stroke, brain damage, hypoxic ischemic encephalopathy (HIE) and cerebral palsy (CP).

An HIE diagnosis is particularly troubling because it means that the baby’s brain has been deprived of oxygen and blood flow.

Are There Any Long-Term Effects of Meconium Aspiration Syndrome?

In most cases, there are no long-term effects for an infant with MAS who is treated appropriately. However, as aforementioned, the baby may have brain damage and other lifelong medical problems if left without oxygen for too long. In some rare instances, an infant may develop permanent lung damage and persistent pulmonary hypertension of the newborn (PPHN).

Kimberly Langdon

Page Medically Reviewed By Kim Langdon, M.D.

Kimberly Langdon, M.D. is a retired board-certified OB/GYN with 19 years of clinical experience. She currently works as a medical writer and featured healthcare expert. She is a regular medical reviewer for Birth Injury Guide.

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