Meconium: What is it? Epidemiology, Etiology, Risks and Complications

It is a dark, sticky material that is normally present in the baby’s intestine at birth.

It is expelled through the stool after birth, after trypsin and other enzymes from the pancreas have acted on it.

Excretion of meconium before birth can be a sign of fetal distress .

Meconium is the product of a baby’s bowel movements in the womb or shortly after delivery.

There are two typical circumstances in which a baby will have a bowel movement while in the womb: when the baby is near term, or when the baby experiences some form of distress, including lack of oxygen.

A bowel movement is a possible physical reaction to stress .

Unlike normal stool, meconium is a thick, sticky substance similar to tar.

Babies are at risk of developing Meconium Aspiration Syndrome when they inhale meconium.

This situation is more common when:

  • The gestation period of the baby is at term.
  • There are problems with the umbilical cord.
  • The baby is not growing properly.

Meconium Aspiration Syndrome is initially treated by trying to clear the lungs, often with a tube after delivery.

If the suction is particularly bad, the baby may need to be put on a respirator.

In the short term, it can cause breathing problems, a low heart rate, and poor muscle tone.

This usually resolves fairly quickly, but in extreme cases Meconium Aspiration Syndrome can lead to death or chronic lung problems.

Meconium can also be used by birth injury lawyers and doctors to help identify the cause and timing of a birth injury.

Fetal distress, including oxygen deprivation, causes the baby’s intestinal muscles to relax, which may be the cause of a meconium-producing bowel movement.

This is an additional factor to be considered by medical experts who will determine whether medical negligence was the cause of a birth injury such as cerebral palsy.

Meconium is a dark green fluid that a newborn baby normally evacuates and contains mucus, bile, and epithelial cells.

However, in some cases, the meconium is expelled while the baby is still in the womb and stains the amniotic fluid. This can range from slight to heavy staining.

It is considered significant if it is dark green or black, with a thick and stubborn appearance.

Meconium is the earliest fecal matter in a mammalian baby.

Unlike subsequent stool, meconium is made up of materials ingested during the baby’s time in the womb: intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile, and water.

Meconium, unlike later stools, is usually a very dark olive green in color and is almost odorless.

The components of meconium, especially bile salts and enzymes, can cause serious complications if the fetus inhales them at any stage of labor.

There are several pathological mechanisms involved in Meconium Aspiration Syndrome, particularly airway obstruction, surfactant dysfunction, inflammation, pulmonary edema, pulmonary vasoconstriction, and bronchoconstriction.

Meconium staining often occurs in conjunction with other causes of fetal distress. It is rare in babies born less than 34 weeks gestation.


The reported figure for babies born with meconium-stained amniotic fluid is 8% to 25% of births after 34 weeks’ gestation.

Meconium Aspiration Syndrome occurs in about 1 to 3% of live births.


Complicated deliveries with meconium-stained amniotic fluid are associated with additional adverse pregnancy outcomes, such as increased rates of labor dystocia, cesarean delivery, and fetal distress.

Risk factor’s

The most common risk factors are:

  • Placental insufficiency.
  • Maternal hypertension and preeclampsia .
  • Oligohidramnios.
  • Smoking.
  • The abuse of cocaine.
  • Maternal age.

Meconium-stained amniotic fluid is of real concern from both an obstetrician and pediatrician’s point of view, as it increases cesarean section rates and causes asphyxia at birth.

Meconium itself is harmless and most babies can pass it while in the womb or during delivery and have no problems.

If meconium is inhaled into the lungs it has the potential to be dangerous and even fatal to newborns.

If meconium gets into the lungs, it can cause a blockage in the airways, which can lead to breathing problems.

Meconium can also cause inflammation of the lungs, leading to infections such as pneumonia.

For a baby to take a deep breath while in the womb, it would need to be severely depleted of oxygen.

There would be various signs of distress long before this happened.

During labor, a baby’s chest is being compressed by contractions and he cannot physically breathe.

Again, if the low oxygen level was causing the baby distress, the baby will likely be removed from the womb, long before your baby runs out of breath.

When babies evacuate the meconium in the uterus, before they are born, there are a number of theories to explain this phenomenon: the baby’s digestive system has matured and began to function.

Meconium passed before 34 weeks’ gestation is rare, only slightly more likely until 37 weeks, then increases in probability with each gestational week starting at 37 weeks.

Reduced oxygen (hypoxia) can cause the intestines to move and the anal sphincter to relax, causing meconium to pass through.

A compression of the umbilical cord during labor, at the time of contractions, or compression of the baby’s head during birth, can cause what is called a vagal response.

The vagus is part of the involuntary nervous system and attends to the body’s unconscious responses, such as controlling gastrointestinal flow.

If the vagal response is stimulated, babies can pass meconium without signs of distress and it can be a normal physiological event.

The reduced levels of oxygen during labor are called hypoxia.

During normal labor, the umbilical cord can compress and slow the flow of blood and oxygen to the baby.

This causes the baby’s heart rate to dip during contractions, but it recovers to a normal rate once the contraction is complete.

Babies generally cope well with this temporary reduction in blood flow.

If the heart rate does not recover, it may be a sign that the baby is not coping and needs to be found out why.

In most cases, a change in position will solve the problem.

However, there are a number of routine procedures and situations in hospital settings that can affect your baby’s blood flow and oxygen, including:

Restriction of movement in labor due to fetal monitoring, inducing or augmenting labor with artificial oxytocin, artificial rupture of membranes if the cord is compressed, clamping and cutting the cord before it has finished expelling, a noisy environment , bright and stressful that disrupts the normal process of childbirth.

Presence of meconium

The presence of meconium before birth

This causes great concern. The most common response is to monitor the baby for other signs of distress, which is usually the fetal heart rate.

If the baby seems to be not doing well, doctors need to make sure the baby is delivered as quickly as possible.

This could induce or accelerate labor, an instrumental birth, or a cesarean section.

It was common practice since the 1970s to suction all babies born with any meconium in the amniotic fluid, regardless of whether they showed signs of aspiration or not.

A syringe or tube is used to suck up any meconium present in the baby’s lungs and airways.

Current practice guidelines no longer recommend routine sucking, but only suck on babies who are flexible, unresponsive, and need resuscitation.

After birth, babies are monitored regularly, their temperature is taken in case of infection, respiration and heart rate will be checked, in some cases blood samples will be taken, and the baby will possibly be in a special hold separate from the mother. .

The presence of intrapartum meconium

If significant meconium staining is observed in labor, there should be continuous fetal monitoring.

The mother should be transferred to obstetric care, if it is safe to do so and delivery is not imminent. If there are signs of fetal distress, a fetal blood sample should be obtained.

If the pH is greater than 7.21, there must be an emergency delivery.

It must be ensured that the advanced resuscitation unit and appropriately trained personnel are available.

There should be no suction before delivery.

The presence of meconium at delivery with a healthy neonate

If the baby is in good condition (Apgar score greater than 5, based on color, tone, heart rate, and respiration), there should be no suction.

The baby should be observed for signs of respiratory distress in the first hour of life, in the second hour, and then every two hours until 12 hours of life.

If there is blood or if there are pieces of meconium in the oropharynx, suction should be used in the upper respiratory tract.

Endotracheal intubation at birth in otherwise healthy meconium-containing babies is no longer recommended.

The presence of meconium at delivery with a sick neonate

An aspiration should be performed.

Initial hypoxic events can cause the baby to have long-term neurological problems, such as seizures, general learning disability, and cerebral palsy.


Infant respiratory distress syndrome

Shortness of breath that usually occurs within four hours after birth and becomes persistent for 48 to 72 hours.

This disease is known as infantile respiratory distress syndrome. If it is not fatal, it resolves within 72 hours.

A surfactant deficiency produces a high alveolar surface tension. The baby should re-inflate the collapsed alveoli with each breath.

Therefore, each breath requires a lot of effort for relatively poor expansion.

Surfactant replacement therapy (synthetic or animal origin) has shortened the duration of the disease and significantly reduced mortality.

Persistent pulmonary hypertension of the newborn

Babies can have persistent newborn pulmonary hypertension as a consequence.

This occurs when fetal circulation persists and blood is diverted from the lungs through the foramen ovale and a patent ductus arteriosus.

Clinical features include cyanosis, tachypnea, and murmur of patent ductus arteriosus.

Treatment usually includes:

  • Supportive measures, including ventilation.
  • Prostacycline infusion.
  • Oxygenation through the extracorporeal membrane.
  • Several promising therapeutic modalities for this condition include oxygen supplementation, mechanical ventilation, nitric oxide, phosphodiesterase enzyme inhibitors, endothelin receptor antagonists.

Chronic lung disease

Children with meconium aspiration can develop chronic lung disease as a result of intensive lung intervention.

Babies with meconium aspiration have a slightly higher incidence of infections in the first year of life because the lungs are still recovering.

mecomial ileum

Meconium ileus is blockage of the intestine due to abnormally thick meconium at the point where the small intestine passes into the large intestine.

Blockage can occur because the thick meconium does not allow intestinal fluid to pass through.

Alternatively, the blockage can cause the intestine to break, twist, or not stay in continuity.

Sometimes complications resulting from the blockage can be seen on ultrasounds performed to monitor the growing baby within the mother.

Meconium ileus is seen mainly in two populations:

  1. Cystic fibrosis patients : Cystic fibrosis patients tend to have thick secretions in their intestines as a result of this disease.
  2. Preterm Newborns: Meconium ileus is sometimes associated with medications to delay labor.

Among the signs and symptoms that appear are; the inability to maintain food, vomiting, swollen belly, no stool.

Sometimes large intestinal loops may have been seen on prenatal ultrasound, abdominal distention, lack of defecation.

If there is a rupture of the intestine, the baby may have low blood pressure.

Diagnosis is made through:

  • Blood tests.
  • X-rays: Plain X- rays can give clues to the cause of the intestinal blockage.
  • Contrast enema: Water-soluble contrast is instilled through the anal opening and x-rays are taken to see the anatomy of the large intestine and where the blockage may be. Sometimes the contrast mixes with the thick stool and allows the stool to pass.
    Treatment for meconium ileus can be done through:
Non-operational management

Nonoperative treatment of meconium ileus can be tried if there are no complications from the blockage (such as bowel turn, rupture, or discontinuity). Attempts to dissolve the thick meconium can be tried.

The water-soluble contrast can be instilled into the anus. Contrast can blend and soften thick meconium, allowing it to break down.

Your baby will have X-rays every 8-12 hours to monitor progress.

If the meconium does not pass completely the first time, but the baby remains stable, the enema can be repeated safely and after an examination by a doctor.


Surgery is necessary if a baby does not respond to enemas and the intestine remains blocked.

Surgery is also required if there are complications resulting from the meconium ileus, such as intestinal rupture, torsion, or discontinuity.

The goal of surgery is to relieve the blockage in the intestine.

If there is an infection, the goal is also to control the infection (for example, to repair a hole in the intestine).

What is done in the operating room depends on many factors, including the baby’s condition, the baby’s size, and damage to the intestine.

Options may include simple bowel flushing, removal of a bowel segment with restoration of continuity, creation of a stoma.

The surgeon will make a decision about the best and safest alternative for the baby while in the operating room.

Preoperative preparation involves administering fluids and antibiotics. Postoperative care is: infants are treated in the neonatal intensive care unit.

The baby will likely need the support of a respirator (ventilator).

It will take days or sometimes weeks for the intestine to become fully functional, so nutrition must be provided through the veins.

Risks of the operation include anesthesia, bleeding, postoperative infection, damage to internal structures that may require further surgery, and recurrence of meconium ileus.

Intestinal obstruction caused by meconium ileus and the complications that accompany it make the baby very sick.

Surgery is often needed to relieve the blockage and help control any existing infection.