Meconium aspiration syndrome, or MAS, occurs when a newborn inhales meconium into its respiratory system. Meconium is a thick, sticky substance found in the intestines of a fetus or newborn.
Meconium may be released into the amniotic fluid when a fetus is in distress. This may occur when a fetus is not getting enough oxygen or nutrients. If this happens, the amniotic fluid surrounding the fetus goes from clear to green. As a newborn takes his or her first breath, or aspiration, the meconium can be inhaled into the lungs. It may partly or completely block the airways. This keeps the baby from getting enough oxygen.
In developed countries, 8% to 20% of the babies born after 34 weeks gestation have meconium-stained amniotic fluid. As many as 1% to 9% of these babies develop meconium aspiration syndrome. MAS is a leading cause of serious illness and death among newborns.
Babies with meconium aspiration syndrome may have the following symptoms: cyanosis, or a bluish skin color, at birthdifficulty breathing or absence of breathinglow scores on the APGAR test, which measures a newborn's overall health statuspoor muscle tonethick, greenish amniotic fluid in the mouth and throat at birth
Many babies with MAS are postmature, which means they have been in the uterus more than 40 weeks.
Following are some of the factors that increase the risk of meconium aspiration syndrome: fetal distress during laborhigh blood pressure in the mother during her pregnancylow levels of amniotic fluid in the uterusplacental insufficiency, which is the failure of the placenta to supply nutrients to the fetuspreeclampsia, a complication marked by swelling and high blood pressurepregnancy that lasts 42 weeks or longersmoking during pregnancyuse of drugs, such as cocaine, during pregnancyinfection in the fetus
Meconium aspiration is not always preventable. The following steps may help in some situations: If at all possible, a baby should be delivered before the pregnancy reaches 42 weeks. Babies at high risk for MAS should be monitored closely after birth. This includes postmature babies, and those who were in fetal distress during labor. If a woman's water breaks at home, she should tell her healthcare provider the color of the fluid.When green-tinged amniotic fluid is reported or seen, labor should be monitored closely. At birth, the healthcare provider should suction out as much meconium as possible from the mouth, nose, and airways.
Fetal monitoring during labor may help detect babies at risk for MAS. At birth, the baby with MAS may have low APGAR scores. The healthcare provider may order arterial blood gases, which detect breathing problems. A chest X-ray may show white patches in the lung fields if the infant has aspirated meconium.
Up to 20% of the babies with meconium aspiration syndrome die from respiratory problems. Other possible complications include the following: atelectasis, which is a collapsed lungchronic lung problemspermanent brain damage pneumoniaseizures
Treatment for MAS may include the following: antibiotics, if an infection is suspectedextracorporeal membrane oxygenation, which uses a special machine to add oxygen to the baby's blood and circulate itinhaled nitric oxidemedications to increase blood flow to the lungsoxygen therapysuctioning meconium from the baby's airwayuse of a ventilator, or artificial breathing machine
Use of a ventilator and other inhalation treatments may cause lung damage. Medications used to treat MAS may cause rash, upset stomach, or allergic reactions.
If pneumonia develops, the baby may need antibiotics for several weeks. Some infants recover completely from MAS. Others may have permanent damage to the lung, brain, or kidneys.
Any new or worsening symptoms should be reported to the healthcare provider.