Meconium aspiration occurs when a baby inhales meconium in amniotic fluid into the lungs, shortly before or just after birth.
This causes breathing problems in the newborn and can lead to irritation of the lungs and infection.
Here we discuss meconium aspiration, the treatment, and long-term complications.
What happens when a baby poops in the womb?
Your baby’s first stool (meconium) is usually passed in the first few hours after birth.
You can read more about meconium in Meconium – What Is It? 9 Things You Need To Know.
Sometimes a baby can pass meconium while still in the womb. This can be a sign of post-maturity, meaning the digestive system is ready to start working.
It can also be a sign of fetal distress.
A sudden and short compression of the cord or head can cause your baby to experience a momentary lack of oxygen, causing the sphincter muscles to relax, and allowing the meconium to be expelled.
Often babies’ heads are quite compressed in the final moments of birth. Some babies have a trail of meconium when their bodies are born.
When a baby passes a stool whilst still in utero, meconium mixes with the amniotic fluid surrounding the baby.
If your waters break and meconium staining is noticed, it can be a cause for concern.
The fluid surrounding your baby should be clear. If it’s greenish, this usually indicates the meconium has only recently been passed. A brownish, yellow color would indicate the meconium in the amniotic fluid was passed sometime earlier and is old.
What are the rates of meconium aspiration syndrome?
According to this recent study, the rate of meconium staining ranges from 8-25% of births over 34 weeks.
It’s rare before 34 weeks, and the incidence increases steadily after 37 weeks. It occurs in up to 40% of pregnancies after 40 weeks (post dates).
Meconium aspiration syndrome occurs in approximately 1-3% of live births.
What happens if my baby swallows meconium-stained amniotic fluid?
Swallowing meconium-stained amniotic fluid isn’t too much of a concern. Meconium is sterile before birth so it’s not going to cause your baby’s digestive system any problems.
The problems occur when the meconium is inhaled, either during labor, or just after birth.
What causes meconium aspiration?
But how does a baby inhale or aspirate meconium if they’re not breathing during labor?
During labor, if babies are distressed and lack oxygen for long enough, it’s possible for them to gasp. They can inhale meconium into the lungs with this movement.
After birth, if meconium is present in their airways, newborns can potentially take it further into their lungs when breathing.
There are a number of factors that increase the chance of meconium aspiration:
- Pregnancy over 40 weeks in length (post maturity)
- Long and difficult labors
- Thick meconium
- Fetal distress
- Smoking or drug use in pregnancy – especially tobacco and cocaine
- Maternal health problems – diabetes or high blood pressure
- Raised maternal age
- IUGR (intrauterine growth restriction)
- Placental insufficiency
- Oligohydramnios (low amniotic fluid levels)
How serious is meconium aspiration?
Meconium aspiration syndrome (MAS) can be serious but, fortunately, if it is treated correctly and quickly, it’s rarely life-threatening.
The condition can vary from mild, resolving in a few days, to severe, leading to life-threatening complications.
When meconium is inhaled, it can partially or completely block the baby’s airways. This makes breathing difficult and reduces the amount of oxygen the baby receives.
When meconium gets into the lungs, it causes irritation and can lead to infections such as pneumonia.
Meconium can also stop surfactant from working. Surfactant is a substance your baby’s lungs need to help them expand properly. Not enough surfactant means your baby can find breathing even more difficult.
Many babies diagnosed with MAS need to be admitted to a neonatal intensive care unit for specialist care and observation.
Most babies usually get better within a few days of treatment. If MAS is left untreated, the condition can be fatal.
What are the signs and symptoms of meconium aspiration syndrome?
If meconium is present in the amniotic fluid, your care providers will watch for signs your newborn is developing meconium aspiration syndrome.
The signs of MAS include:
- Breathing problems at birth
- Blue-ish skin color (cyanosis)
- Poor muscle tone or ‘floppy’ at birth
- Abnormal breath sounds such as grunting
- Nasal flaring
- Chest recession (baby’s ribs and chest will be pulled in).
The symptoms newborns will display if they’ve inhaled meconium include:
- Poor Apgar score
- Low heart rate (<100/min)
- Low oxygen levels
- Low blood pressure
- Rapid breathing.
How is meconium aspiration diagnosed?
Meconium aspiration is diagnosed as any form of breathing problem in a newborn immediately after birth, with meconium-stained amniotic fluid.
To diagnose MAS your care provider will order investigations such as:
- Blood gas analysis
- Blood cultures
- Chest x-ray.
What’s the treatment for meconium aspiration?
In the past, a baby with meconium-stained amniotic fluid was suctioned when the head was born. Suctioning is no longer routine practice and isn’t recommended by the American College of Obstetrics and Gynaecology (ACOG), leading experts in maternity care.
Current guidelines from ACOG state that in the presence of meconium, a newborn who is vigorous, with a good heart rate (>100 beats/min), only requires monitoring for signs of MAS for the first 12 hours of life.
Babies who aren’t vigorous at birth, with a poor heart rate (<100 beats per/min) and poor muscle tone, are likely to need immediate suctioning.
Care providers will aim to clear the baby’s airways as much as possible, to avoid meconium being inhaled.
After these emergency measures, infants will be treated with antibiotics to reduce the chance of developing an infection.
They may need ongoing support from a breathing machine and supplemental oxygen, delivered via a nose tube. Newborns need to be kept under a warmer to help regulate their temperature so they don’t expend more energy.
Newborns with MAS will be monitored in the special care nursery for signs of infection. They will have frequent blood tests and might need ongoing respiratory support.
What are the long term effects of meconium aspiration?
Newborns with uncomplicated MAS usually improve within a few days or weeks. They might have rapid breathing for some time after birth, but it’s rare there’s any permanent lung damage.
Babies with severe cases of MAS have a slightly increased risk of lung infections in the first 12 months, as the lungs are still recovering. This should improve with age, as their lungs develop new air sacs.
Permanent lung damage is rare.
Can meconium aspiration be prevented?
The most obvious way to avoid a stressed baby is to have a calming birth environment and supportive provider.
If a woman is disturbed and her stress is high during labor, contractions might slow or stall. This can lead to a cascade of interventions to hurry things along, further contributing to fetal distress.
Slow Labor? 8 Natural, Effective Tips To Get Things Going has tips on how to deal with labor slowing or stalling.
If there is meconium in the amniotic fluid and your baby’s heart rate remains reassuring, you should be supported to continue to labor in an upright position.
Contractions in this position will push fluid out of your baby’s lungs and down out of the mouth and nose.
Delayed cord clamping allows your newborn to receive blood flow and oxygen while transitioning to breathing air into the lungs.
To reduce the risk of serious complications related to meconium, the 2014 ACOG guideline suggests induction of labor between 41 and 42 weeks.
Compared with expectant management, induction at this stage has been shown to reduce incidence of meconium aspiration, and fewer deaths in the first week after birth.
It’s important to remember, meconium staining can occur in the absence of fetal distress, and not all babies who become stressed pass meconium.
It’s rarely a problem, and care providers can help prevent it by avoiding the use of unnecessary interventions that increase the likelihood of fetal distress.
Parents should be aware of the signs of MAS and seek professional attention if they become concerned about their baby’s breathing.