Placental Insufficiency

Blood flows between the mother and the baby through the placenta. The placenta transports nutrients and oxygen to the baby. Oxygen-rich blood from the mother travels through the placenta and umbilical cord to the baby. 

Placental insufficiency is the most frequent cause of intrauterine growth restriction (IUGR). IUGR is when the unborn baby is growing too slowly. Placental insufficiency can also cause oligohydramnios (low amniotic fluid) and preeclampsia (high maternal blood pressure).

A diagnosis of placental insufficiency often includes an initial finding that the baby is small and has IUGR.

Next, the mother is usually diagnosed with oligohydramnios. A prenatal test called a Doppler study may discover a decreased flow in the baby’s heart. A decreased flow can progress to absent flow and then reverse flow, which can be quite serious.

The baby may have fetal distress, which registers on the fetal heart rate monitor as non-reassuring heart tones. The baby’s heart rate may become too fast (tachycardic) as the baby’s heart tries to increase blood flow. The baby’s heart tracings get worse (increasingly non-reassuring) as her oxygen reserves run out.

Placental insufficiency can cause severe injury to the baby. When blood flow lessens, the baby becomes increasingly oxygen-deprived. Then, the baby develops a high likelihood of acidemia at birth. This means the blood is acidic from the lack of oxygen. 

Acidemia can also develop from a prolonged period of decreased blood flow and oxygen, or anaerobic metabolism. Anaerobic metabolism occurs when there is insufficient oxygen to meet the baby’s energy needs.

Placental insufficiency can deprive the baby of enough oxygen and nutrients while in the womb. These conditions can cause IUGR. If the baby is growing too slowly, they may not be able to tolerate labor and delivery well. 

The standard of care may require early delivery at 34 – 37 weeks depending on prenatal testing. The physician monitors the mother very closely prenatally.

Medical staff will regularly assess the baby’s well-being and the amount of amniotic fluid. If either of these becomes a concern, then they should immediately deliver.  

Medical professionals may decide to deliver the baby before 34 weeks. If they do, they should perform an amniocentesis to help evaluate fetal lung maturity. 

The mother usually receives corticosteroids within 24 hours of the early delivery. This medication helps the baby’s lungs mature, which can help which can help the baby breathe after birth. Corticosteroids also help prevent brain bleeds in the baby.

The medical staff must follow standards of care and deliver the baby early with cases of placental insufficiency. Failure to do so can deprive the baby of oxygen and nutrients for too long. These conditions can result in permanent brain injury.

Due to the severe consequences of placental insufficiency, physicians must promptly diagnose and manage this condition. Medical staff should monitor the condition closely with frequent non-stress tests, biophysical profiles, and Doppler studies. Mothers with placental insufficiency should consult maternal-fetal specialists.  

Sometimes the physician will decide to deliver the baby early by C-section delivery. An early delivery safely removes the baby from the oxygen-depriving conditions. 

Babies who have IUGR do not tolerate labor and contractions very well. Medical professionals must closely monitor the baby. They should be ready to perform an emergency delivery at the first sign of distress.

Placental insufficiency may have severe consequences. If medical professionals do not address and monitor the condition, placental insufficiency can cause:

HIE is a brain injury caused by insufficient oxygen in the baby’s brain. Complications from placental insufficiency can cause decreased blood flow to the baby and a lack of oxygen, resulting in HIE.

HIE often leads to a later diagnosis of cerebral palsy, seizure disorders, or developmental disabilities.

Cerebral palsy causes the child to have problems with movement, balance, coordination, and posture. Cerebral palsy causes problems in the part of the brain controlling muscle movements. 

Children with cerebral palsy may have all limbs affected, or they may only have one or two limbs that don’t function properly. Fine motor function is also usually affected, which can make it hard for a child to hold a crayon or a small piece of cereal. Eating and talking may be difficult because of problems with oral-facial muscles.

Brain injuries like HIE may cause the baby to have seizures very soon after birth.  HIE is the most common cause of seizures in a baby. Seizures can also cause further injury to a baby’s brain. Physicians must recognize and treat seizures as soon as possible. 

Seizures occur when there is uncontrolled electrical activity in the brain. This causes brain disturbances, altered consciousness, and convulsions.  

In many babies, outward signs of seizure activity may not be evident.  If there is a chance the baby has a brain injury, medical teams should perform frequent EEGs on the infant. The EEGs will detect abnormal electrical activity in the brain. Several neonatal intensive care units throughout the country have continuous EEG monitoring.

Babies with IUGR are at risk of having low blood sugar, or hypoglycemia. IUGR can cause the baby to not have enough nutrients, including glucose. Glucose is essential for brain function. 

Neonatal hypoglycemia is very serious. It means that the baby’s blood sugar (glucose) level is lower than normal. Untreated hypoglycemia can cause permanent brain injury and cerebral palsy.

Meconium aspiration can occur when the mother has placental insufficiency. Meconium aspiration is when a baby has a bowel movement in the womb and inhales a mixture of stool and amniotic fluid. This typically occurs when the baby experiences oxygen deprivation and distress.

Meconium aspiration can cause major breathing problems after birth. A baby who inhales meconium may have respiratory distress and may develop pneumonia. These conditions can cause even more oxygen deprivation in the baby.

Babies with meconium aspiration often need a breathing machine (ventilator) for help with breathing. However, this increases the baby’s chances of having overventilation injuries.

Uteroplacental perfusion refers to blood flow from the uterus and placenta to the developing baby. If blood flow is normal, the placenta sends enough oxygen and nutrients to the baby. The baby may not grow properly or receive adequate oxygen and nutrients if the blood flow is less than normal.

During routine prenatal screening, medical professionals often use color Doppler to detect any abnormalities in uteroplacental perfusion. Doppler tests allow them to diagnose and treat the underlying cause of any perfusion issues. Causes of perfusion issues can range from maternal hypertension (high blood pressure) to structural uterine abnormalities to issues with the umbilical cord. They may also use non-stress tests (NSTs) or biophysical profiles (BPPs).

If blood flow is too low, medical staff should perform a timely delivery to prevent harm to the baby.

Placental resistance, or resistance in uteroplacental blood flow, is a measure of how well blood is flowing through the placenta and uterus to get to the baby. During routine prenatal testing, physicians check placental resistance using Doppler flow studies.

One of the most common concerns with placental resistance is high resistance. Preeclampsia and other risk factors may cause high placental resistance. When blood pressure increases, resistance increases, which can mean that overall blood flow to the baby decreases. This can cause fetal growth restriction (FGR). 

Medical professionals must promptly address any type of insufficient placental blood circulation or placental insufficiency.

A mother with placental insufficiency usually does not have any symptoms. Physicians may look for signs of placental insufficiency If prenatal testing is abnormal or the baby is small for its gestational age. Late decelerations are one indication that there may be placental insufficiency. There may be no other signs of reduced blood flow to the placenta initially.

Another way to diagnose placental insufficiency is through measurements and ultrasounds. These tests can indicate that the uterus (womb) is not growing as it should. 

Physicians should measure a mother’s uterus at every prenatal visit, starting about halfway through the pregnancy. If the uterus is too small, medical staff should perform an ultrasound. The ultrasound measures the baby’s growth and size, assesses the size and placement of the placenta, and indicates if the amniotic fluid is low.

Doppler ultrasounds give information about the blood flow in the placenta and baby.  Physicians can perform Doppler velocimetry at the beginning of the third trimester. This test measures blood flow in the mother and baby’s blood vessels. The measurements give physicians information about uteroplacental blood flow and the baby’s responses to physiological challenges.  

When vessels in the placenta develop abnormally, the placental blood flow and fetal blood flow change. The baby’s blood pressure and heart rate also change. The abnormal development causes circulation problems in the placenta and baby.

Doppler measurements from certain blood vessels, like the umbilical artery, can show  compromise and dysfunction of the placenta’s blood vessels. The baby may become significantly oxygen-deprived and further circulation problems may develop. The Doppler’s blood flow measurements correlate with acidosis in the baby (whether the baby is getting enough oxygen).