Babies have functioning digestive systems long before they’re born. Of course, they take in all their nutrients through the umbilical cord rather than through food. However, they do swallow amniotic fluid, mucus, epithelial cells, and other material in the womb. That material collects in the baby’s lower intestines to form meconium. Meconium is thick, gooey, and dark. It’s the first thing a baby passes after birth.
In some cases, the baby expels meconium while still in the womb or during delivery. When that happens, the baby is at risk for breathing in amniotic fluid tainted with meconium. Meconium is sterile and won’t cause infection on its own, but it can affect the baby’s ability to breathe. The sticky substance can block the baby’s airways, affect the baby’s ability to exchange oxygen and carbon dioxide, and irritate the baby’s lung tissue. This is called meconium aspiration syndrome.
Diagnosing Meconium Aspiration Syndrome
Meconium aspiration syndrome may be identified by signs including meconium in the amniotic fluid, breathing distress, and low Apgar scores.
Meconium in the Amniotic Fluid
The first and most obvious symptom of meconium aspiration syndrome is the presence of meconium in the amniotic fluid. Amniotic fluid is mostly clear, while meconium is thick and greenish-black. If there are streaks of darker material in the amniotic fluid released during delivery or if the amniotic fluid has a green color, it’s likely that the baby has released meconium and may be at risk for meconium aspiration syndrome. The presence of meconium in the amniotic fluid does not necessarily mean the baby will suffer from meconium aspiration syndrome — only about 5% of babies who release meconium in the womb will develop other symptoms.
See also: Causes of Meconium Aspiration Syndrome
Babies born at term should be able to breathe on their own — healthy babies typically cry as soon as they’re born. Babies with meconium aspiration syndrome may have a difficult time breathing. They may be straining to breathe, breathing too fast or too slow, or not breathing at all. Babies experiencing this type of respiratory distress may grunt while exhaling.
Babies who are struggling to get enough oxygen may appear “cyanotic,” which means the baby will look blue because of the lack of oxygen in the blood.
If the baby appears to be in respiratory distress, your doctor will use a stethoscope to listen to the sound of the air as it passes through your baby’s lungs. The lungs of babies with meconium aspiration syndrome often make crackling or rattling noises. Your doctor may also use a chest x-ray to look for patches or streaks of meconium on the lungs.
Low Apgar Scores
The APGAR test is performed 1 minute after delivery and again 5 minutes later. It’s a measure of how well the baby tolerated delivery and how well it’s doing outside the womb. The test measures the baby’s breathing, heart rate, muscle tone, skin color, and reflexes. Healthy babies will cry, react to stimuli such as pinching, and actively move their limbs. They will have regular heart rates and pink skin tone.
Babies with meconium aspiration syndrome are typically struggling to breathe. That makes the heart rate change and can leave the skin blue. Babies in serious respiratory distress may be floppy and may not react to stimuli.
What Happens When Babies Swallow Meconium
Meconium aspiration syndrome can cause obstruction of the baby’s airways, pneumonitis, and dysfunction of the baby’s lungs.
Meconium is sticky and thick and can clog the baby’s airways. This can cause the “ball-valve effect,” or “hyperdistension of the alveoli.” The baby’s airways expand as the baby inhales, allowing air into the lungs. The airways then contract as the baby exhales, allowing the meconium to block the passage and trapping air in the lungs. That can lead to hyperinflation of the lung. In serious cases, the hyperinflated portion of the lung may rupture and leak air out into the baby’s chest cavity.
When a rupture allows air into the cavity surrounding the lungs, that air then pushes back on the lung itself. This may cause the lung to collapse. A lung collapse may be called a pnemomediastinum, a pneumopericardium, or a pneumothorax, depending on which part of the lung collapses.
“Pneumonitis” is a general term referring to inflammation of the lungs. You’ve probably heard of pneumonia, which is a type of pneumonitis. Lung inflammation may be caused by a bacterial or viral infection. It may also be caused by molds or radiation exposure. Babies with meconium aspiration syndrome are at risk for chemical pneumonitis, which is caused by the introduction of foreign material into the lungs. Symptoms include breathing that sounds wet or gurgling, cough, and difficulty breathing.
Meconium contains proteins and enzymes that irritate the lung tissue and cause it to swell. In serious cases, chemical pneumonitis may cause parts of the baby’s lung to die and collapse.
The process by which your lungs exchange carbon dioxide and oxygen is a complicated one, dependent on a number of physical and chemical processes. Pulmonary surfactants are a crucial part of a healthy lung. Pulmonary surfactants are a fluid made of proteins and fats that form a film on the surface of the alveoli — the tiny chambers where oxygen is pulled into the blood and carbon dioxide is pulled out. The pulmonary surfactants make it easier for these gases to pass through the alveoli.
Meconium can interact with pulmonary surfactants and strip them away from the alveoli. That makes it harder for the baby to get enough oxygen into the blood and get rid of carbon dioxide. Lung lavage using diluted surfactant to wash out meconium from the lungs can be beneficial.
Long-Term Effects of Swallowing Meconium
In the short term, your baby may need treatment for pneumonitis or the effects of a rupture. About 15% to 30% of babies with meconium aspiration syndrome develop pulmonary air leaks. Babies who aspirate meconium may also require suction of the mouth and upper airways to clear out any meconium there.
In severe cases, your baby may need to be placed on a ventilator. That ensures that the baby is getting enough oxygen. It also takes the strain off of the baby’s lungs to give them a chance to rest and heal. Babies with meconium aspiration syndrome may be more vulnerable to lung infections and pneumonia for the first year or so after birth. They may also suffer from reactive airway problems early in life.
Oxygen deprivation as a result of meconium aspiration syndrome can have serious side effects, including brain damage. Prompt diagnosis and treatment are crucial to ensure that your child is getting enough oxygen. Fortunately, most babies who suffer from meconium aspiration syndrome do not suffer any long-term effects, and have a complete recovery of their pulmonary function.