When a woman first becomes pregnant, the amount of information given to her about prenatal care may be overwhelming. Throughout this page, our birth injury team will explain the prenatal tests that physicians perform to ensure the health and proper development of a newborn baby. The main goal of these tests, called antenatal or prenatal tests, is to identify babies at risk of brain injury so that permanent brain damage and injury can be prevented. Conditions present during pregnancy can cause a baby to be deprived of oxygen, and tests performed in the physician’s office can detect these problems in order to prevent permanent brain damage. Injury to a baby’s brain that occurs before, during or near the time of delivery can cause conditions such as hypoxic ischemic encephalopahty (HIE), cerebral palsy, periventricular leukomalacia (PVL), intellectual and developmental disabilities, hydrocephalus, and more.
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At Reiter & Walsh, P.C., our team of birth injury attorneys and professionals have exclusively focused on HIE, cerebral palsy and birth trauma cases since the firm’s inception in 1997. We have helped hundreds of birth injured children and their families secure resources for therapy, treatment, care and lifestyle adjustments. If your child experienced a birth injury and now has seizures, HIE, brain damage, cerebral palsy or any other long-term condition, we encourage you to contact Reiter & Walsh today. Our award-winning Michigan birth injury and HIE lawyers are available 24/7 to speak with you.
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Prenatal Testing, Oxygen Deprivation, HIE and Infant Brain Damage
Oxygen deprivation (hypoxia) and acidosis (acidity of the baby’s blood due to oxygen deprivation) represent the final pathway to infant brain damage. If a baby is being deprived of oxygen, prenatal tests will show certain signs, including:
- Decreased amniotic fluid
- Decreased fetal movement
- Changes in blood flow
- Slow fetal heart rate
When a baby is hypoxic, receptors in the brain and vessels send signals that slow the heart rate. During antenatal testing, this may show up as late decelerations. A late deceleration means the baby’s heart rate is decreased below the baseline heart rate in response to a contraction, and this decrease occurs towards the end of the contraction.
When the baby is receiving decreased levels of oxygen, movement in the womb will decrease in an attempt to conserve oxygen and energy. When the baby completely stops moving around in the womb, it is usually a sign of ongoing oxygen deprivation in the brain and central nervous system. This typically signifies brain injury.
When a fetus is deprived of oxygen, amniotic fluid levels decrease. This happens because the baby’s body will direct blood flow to the most important organs, such as the heart and brain, and away from the kidney, which produces urine. Urine production is then decreased, and this causes a decrease in amniotic fluid, since urine is one of the fluids that comprises amniotic fluid.
Prenatal Tests Used to Detect Fetal Oxygen Deprivation and Hypoxic Ischemic Encephalopathy (HIE)
When a baby starts to show signs of oxygen deprivation, it is known as fetal distress. Prenatal tests that detect the major indications of fetal distress are listed below.
Prenatal Testing: Nonstress Test (NST)
The nonstress test, or NST, can be performed as early as the beginning of the third trimester, and it can be performed as late in the pregnancy as needed. It is most frequently performed between weeks 38 and 42 of the pregnancy.
The nonstress test is performed to ensure that unborn babies’ heart rates increase while they move or kick, just as our heart rates increase when we exercise. The NST provides information about the baby’s health by showing the baby’s heart rate in response to movement. When babies don’t receive sufficient supplies of oxygen from the placenta, their heart rates will not accelerate when they move. This is known as a nonreactive test. If the baby’s oxygen supply is adequate, heart rate accelerations will be evident; this is known as a reactive test. An acceleration is an increase in the baby’s heart rate for at least 15 seconds, and the increase must be at least 15 beats per minute. The presence of accelerations is an indication that the baby is receiving enough oxygen-rich blood. During labor, accelerations are one of the most important signs of the baby’s well-being.
The test is typically performed if a mother has gone past her due date. It is also performed if the mother’s pregnancy is high-risk. Reasons for an nonstress test include the following:
- The mother has high blood pressure (preeclampsia)
- The mother has gestational diabetes or diabetes treated with medication
- The mother has some other medical condition that could affect the pregnancy
- The baby appears to be small or not growing properly (fetal growth restriction; intrauterine growth restriction)
- The baby is less active than normal
- There is too much or too little amniotic fluid (oligohydramnios)
- The mother has had a procedure, such as an external cephalic version (which turns a baby in breech position to the proper position) or a third trimester amniocentesis (to determine if the baby’s lungs are mature enough for her to be born or to check for a uterine infection, such as chorioamnionitis)
- The mother has previously lost a baby during the second half of pregnancy. When this is the case, NST testing may begin as early as 28 weeks.
- The baby has been diagnosed with an abnormality or birth defect and needs to be monitored.
Prenatal Testing: Contraction Stress Test (CST)
A contraction stress test (CST) is performed at 34 weeks of gestation or later to determine if the unborn baby will stay healthy during the period of reduced oxygen levels that normally occur during contractions. In other words, a CST is performed to ensure that the baby and placenta are healthy and that the baby can receive adequate amounts of oxygen from the placenta during labor.
During a CST, the mother lies on her left side. Two devices are attached to her abdomen; one monitors the baby’s heartbeat and the other records contractions. A machine records contractions and the baby’s heartbeat on two separate lines on graph paper for the physicians to interpret. If the mother doesn’t have contractions for the first 15 minutes of the test, she may be given Pitocin (oxytocin), which can induce contractions.
The CST is based on the premise that uterine contractions temporarily restrict oxygen delivery to the baby, and that a baby who is oxygen-deprived will have multiple late decelerations. Contractions decrease oxygen supply because during a contraction, the flow of oxygen-rich blood going to the baby slows down. When the placenta is healthy, it has extra stores of oxygen-rich blood ready to supply the baby with the oxygen needed during or after a contraction. If the placenta isn’t functioning properly, however, the baby won’t receive enough oxygen and his or her heart beat will slow down after a contraction.
The CST is like the NST except the fetal heart rate is evaluated in response to contractions as well as accelerations. The CST is not used very often anymore because it is riskier and more expensive than other tests. Indeed, administration of Pitocin is risky because there is no way to predict how it will affect each individual mother and baby. In addition, labor induction drugs such as Pitocin are contraindicated in a number of conditions, such as placenta previa.
Prenatal Testing: Amniotic Fluid Volume (AFV)
Amniotic fluid volume (AFV) is dangerous for the baby if it is too low (oligohydramnios) or too high (polyhydramnios). Amniotic fluid is the protective, sterile fluid that surrounds the fetus in the womb. Abnormalities in AFV are associated with many different pregnancy complications, including premature rupture of the membranes (PROM), preterm birth, unstable or abnormal fetal presentation (such as face and breech presentations), placental abruption, cord compression, fetal growth restriction and adverse perinatal outcomes, such as HIE (hypoxic ischemic encephalopathy), which can cause cerebral palsy, PVL and intellectual and developmental disabilities (I/DD).
An ttrasound can obtain a measurement called the amniotic fluid index, or AFI. AFI is calculated by measuring the depth of the amniotic fluid in four sections of the womb and adding them together. Near term, an AFI of 9-18 centimeters is considered normal, 5-8 is considered borderline, and 5 or below is considered abnormal. A sudden decrease in amniotic fluid or a significant decrease over a short period of time is considered abnormal even if the AFI is above 5.
At 20-35 weeks of gestation, the AFI in a healthy pregnancy is approximately 14 cm. At weeks 34-36, the amniotic fluid starts to decrease in preparation for birth.
An alternative to the AFI is to determine the maximum pool, which is when the single deepest vertical pocket of amniotic fluid is identified by ultrasound and measured. This is part of the biophysical profile (BPP), which we’ll discuss in the next section.
Amniotic fluid normally increases steadily to about one liter by 34-36 weeks, and then decreases thereafter; most studies report a decrease of about 25% per week. The rate of decline may be as high as 150 milliliters per week at 38-43 weeks. In some cases of oligohydramnios, the volume may be reduced to only a few mL.
Polyhydramnios typically is defined as having around 2,000 mL of amniotic fluid, > 8cm maximum pool, or an AFI > 25 cm. It can be caused by the baby producing too much urine, decreased fetal swallowing, and increased water transfer across the placenta to the baby.
If AFV is abnormal, the baby may need to be delivered early, especially if the cause is unknown. Factors used to determine if a baby should be delivered early include whether other factors indicate the baby is in distress, such as an abnormal or nonreassuring heart rate, or whether the baby’s lungs are mature.
Prenatal Testing: Biophysical Profile (BPP)
The biophysical profile (BPP) can be performed as early as the beginning of the third trimester, and is performed using an ultrasound over a 30 minute period. BPP includes the following:
- The NST
- Ultrasonographic measurement of the AFV
- Observation of the presence or absence of fetal breathing movements
- Gross body movements
- Tone (reflex and extension movements)
Each test parameter has points assigned to it. The BPP is used to assess indicators of sudden onset hypoxia as well as hypoxia that has been ongoing. Sudden onset (acute) hypoxia is reflected in the NST, breathing, and body movement portions of the BPP, while chronic (ongoing) hypoxia is reflected in the AFV portion.
The modified BPP (mBPP) is comprised of the NST as a measure of acute oxygenation and the AFI as a measure of longer term oxygenation.
The BPP predicts the presence or absence of fetal asphyxia (severe hypoxia) as well as the risk of death during the antenatal period (the short period after birth). When the BPP identifies a compromised baby, steps must be taken by the physician before progressive acidosis causes death or permanent brain damage in the baby. One of the steps that may be necessary is delivery by an emergency C-section.
Prenatal Testing: Doppler Velocimetry
Doppler velocimetry also can be performed at the beginning of the third trimester. This prenatal test measures blood flow in the mother and baby’s blood vessels and gives physicians information about uteroplacental blood flow and the baby’s responses to physiological challenges. When vessels in the placenta are developing abnormally (as in preeclampsia, hypertension, or sickle cell disease), there are progressive changes in placental blood flow, as well as in fetal blood flow, blood pressure and heart rate. This causes circulation problems in the placenta and fetus. Doppler measurements from certain vessels, such as the umbilical artery, can indicate severe compromise and dysfunction of the group of vessels in the placenta. When compromise to these vessels is present, the baby may become significantly oxygen-deprived, and eventually, certain vessels will constrict and others will dilate to direct blood flow to the most important organs in the baby, the brain and heart. After this occurs, circulation through the umbilical artery may change even more in response to ongoing severe oxygen-deprivation. Blood flow measurements that the Doppler picks up correlate with acidosis in the baby.
In contrast to most other fetal assessment tests, Doppler tests have been rigorously researched. Doppler measurements are very specific and show flow in different vessels and can pinpoint flow in the maternal component of the placenta. Any abnormal Doppler finding needs very close monitoring and immediate consideration as to the timing of delivery.
Medical Malpractice and Prenatal Testing Errors
According to care standards, all medical personnel must follow standards of care in prenatal testing. Regular tests are required, and if the pregnancy is high-risk or the mother has signs of a pregnancy complication, appropriate prenatal testing must take place. When prenatal testing reveals health problems with the mother or baby, medical professionals must intervene.
Medical professionals must constantly be on the lookout for fetal distress. When fetal distress is present, medical personnel must act promptly and treat the condition causing it, since fetal distress almost always is an indication that the baby is not receiving enough oxygen. Often, delivery by emergency C-section is the best intervention when a baby is in distress. It is negligence if physicians dismiss signs or indications of fetal distress. Failure to perform appropriate prenatal tests and appreciate fetal distress is medical malpractice.
Trusted Legal Help for Birth Injuries
If you or your loved one were permanently injured as the result of prenatal testing errors, you could be eligible for compensation from a medical malpractice case. Birth injuries such as cerebral palsy, HIE (hypoxic ischemic encephalopathy), PVL (periventricular leukomalacia), intellectual and developmental disabilities, and others often require a lifetime of special care needs. Our team of birth injury attorneys and professionals have helped families like yours secure the resources necessary to pay for long-term care and support.
We encourage you to contact our award-winning birth injury attorneys today for a free consultation. We will review the medical records and determine if needed prenatal tests were not performed, your baby’s fetal distress was unappreciated or mismanaged, or any other act of negligence occurred. If your child was injured due to malpractice, our birth injury and HIE lawyers will fight to obtain the compensation your child deserves for medical care, therapy and a secure future. Our firm has numerous multimillion dollar verdicts and settlements that attest to our success and no fees are paid to our firm until we win your case.
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Video: Reiter & Walsh, P.C. HIE Lawyers Discuss Birth Asphyxia and Hypoxic Ischemic Encephalopathy
Watch a video of Michigan HIE lawyers Jesse Reiter and Rebecca Walsh discussing the importance of prenatal testing to help prevent birth injuries and birth asphyxia.