Asphyxia is the most common cause of brain injury at birth. Just like the word “asphyxia” suggests, asphyxia in the birthing process happens when the unborn baby does not get enough oxygen through the baby’s lifeline: the umbilical cord, which is connected to the placenta (which is the trading post between the baby’s blood and the mother’s blood), which is attached to the mother’s uterus.
During labor and delivery, doctors and nurses watch the baby’s heartbeat on the electronic fetal monitor for any warning signs that a baby is at risk for asphyxia. If the fetal monitor shows a pattern of slow-downs in the baby’s heart rate late in the contraction or variably during the contraction, this can be a sign of a problem.
Fetal Monitoring
The electronic fetal monitor puts out a strip of paper, plus an electronic video and audio signal, showing two things: the baby’s heart rate and the mother’s contractions. Here is an example:
The top bar graph is the baby’s heart rate. Normal is a range from 120 to 160 beats per minute. On the graph, each horizontal box represents 10 seconds, and the slightly darker lines show one minute. Each vertical box represents a change in heart rate of 10 beats per minute. This baby’s heart rate on this strip ranges from about 120 to 160 beats per minute, completely normal.
The bottom graph shows the strength of the mother’s uterine contractions. When the line gets near the bottom, the uterus is relaxed. In determining if a baby is under distress, it is important to look for drops in the baby’s heart rate – decelerations – in connection with the timing of the uterine contractions. There are three basic types of decelerations: early, late and variable.
Early Decelerations: Early decelerations (decels) have a gradual drop in the baby’s heart rate with the onset of the drop occurring with the onset of a contraction. The U-shape of the early decel mirrors the upside-down-U shape of the contraction. An early deceleration is entirely normal and is not associated with lack of oxygen to the baby.
Late Decelerations: Late decelerations are like early decels except for their timing: the start of a late deceleration occurs after the start of the contraction. Late decelerations can mean the baby is not getting enough oxygen from the mother’s placenta. The size and depth of a late decel is not the key, because even subtle late decels can be worrisome. As the contraction builds, blood flow through the placenta is diminished, leaving the baby to rely on its own reserves. When reserves are inadequate, the baby’s heart rate decreases and a late decel occurs. After the contraction ends, normal blood flow usually resumes and the heart rate recovers.
Variable Decelerations: Variable decels can occur before, during, or after a contraction, or when no contraction is present (nonperiodic). It is characterized by an abrupt drop in the baby’s heart rate, followed by an abrupt return to baseline. Variable decels can vary in size, timing, depth and duration. Also, atypical variable decelerations can occur, which are more diagnostic of a fetus at risk.
Variable decelerations go with cord compression. The duration of the decel may be tied to the period of time that the cord is compressed. When the umbilical cord is compressed, it causes an increase in fetal blood pressure, reduces oxygen supply to the baby, and activates responses in the baby’s brain which result in a decrease in heart rate and the development of variable decelerations. As hypoxia becomes prolonged, the decelerations may become deeper and last longer.
“Beat-to-beat” variability: Another important hallmark of baby well-being on a fetal monitor strip is the “beat-to-beat variability” – bounciness — of the baby’s heart rate. (This is also called “short-term variability” in the current nomenclature of obstetricians.) The fetal heart rate varies from one beat to the next, because two branches of the nervous system control changes in the heart rate. The sympathetic branch is constantly trying to speed up the heart, while the parasympathetic branch is trying to counteract this by slowing the heart. These beat-to-beat changes are referred to as variability. Normally, the sympathetic and parasympathetic nervous systems have equal opposite effects on the heart rate, resulting in a consistently variable heart rate pattern. When the equilibrium is altered, accelerations and decelerations may occur. Further, the reduction or cessation of oxygen flow to the brain can lead to a decrease or loss of variability. This shows on the fetal monitor strip by the baby’s heart rate becoming less bouncy and more flat, with little change from beat to beat.
The next slide shows a prolonged deceleration in the baby’s heart rate, down to as low as 80 beats per minute, while at the same time the mother’s uterus is not completely relaxing between contractions. (This is also known as uterine hyperstimulation.) The gaps show that the monitor is frequently failing to pick up the signal from the baby’s heart. This baby went on to suffer profound brain injury because the mother’s uterus ruptured and all oxygen to the baby was lost for a number of minutes. The nurse-midwife was trying to have the mother undergo a vaginal delivery after a prior caesarean section (“VBAC” – vaginal birth after caesarean).
Prenatal testing in late pregnancy
Before a monther goes into labor, tests are available to determine if a baby can safely undergo the stresses of labor and delivery. The standards for safe baby delivery require some type of test when the baby has risk factors for insufficient oxygen, or other specific clinical situations develop, such as:
- decreased fetal movement,
- high blood pressure disorders (Pregnancy-induced hypertension or pre-eclampsia),
- diabetes (either pre-existing or occurring only in pregnancy, which is called gestational diabetes),
- oligohydramnios (reduced amniotic fluid, meaning the baby is not urinating normally in the uterus),
- intrauterine growth retardation (baby is small for age), and
- post-dated pregnancy (baby is overdue).
Several tests can help the doctor determine if the baby has a problem. These all rely on a combination of watching the baby’s heartbeat and looking at the baby inside the uterus with ultrasound. These tests include:
- fetal movement counting,
- the non-stress test (“NST”) (watching the heartbeat for reassuring accelerations over a period of 30 to 60 minutes before labor starts),
- the contraction stress test (“CST”),
- the oxytocin challenge test (“OCT”) (watching how the baby’s heartbeat responds to an induced contraction in the mother);
- the biophysical profile (“BPP”) (which measures the baby’s movement, breathing, muscle tone, and amount of amniotic fluid in combination with the heart beat),
- ultrasound, and
- doppler flow testing.
These tests are used to gather information about whether the baby is healthy enough to withstand the stresses of labor and whether the baby might benefit from early delivery.
High blood pressure in Pregnancy
Clinical Signs and Symptoms
Hypertension (high blood pressure) occurs in almost one in ten pregnancies. Pregnancy may induce hypertension or aggravate a woman’s pre-existing hypertensive condition. When a woman develops pregnancy-induced or aggravated hypertension, the pregnancy may continue to term. However, the risk of maternal or fetal death or injury increases in pregnancies complicated by hypertension. The condition may lead to fetal growth retardation, premature birth, and uteroplacental insufficiency (an insufficient environment for the baby because of loss of blood flow from the uterus to the placenta), which can diminish the flow of oxygen and nutrients to the fetus and cause fetal distress.
An obstetrician may respond to these potential complications by checking the mother’s blood pressure at more frequent intervals, hospitalizing the mother for testing and observation, initiating drug therapy, ordering laboratory tests, or terminating the pregnancy.
Hypertensive conditions of pregnancy are classified by when the hypertension is diagnosed and what other clinical findings accompany it. For example, when the patient develops high blood pressure before becoming pregnant, or is diagnosed before the 20th week, the condition is called chronic hypertension. This may be mild or severe, depending on the blood pressure measurement. Patients who have chronic hypertension are at increased risk for developing more serious complications at a later stage of the pregnancy.
If the patient develops hypertension after the 20th week, the condition is called pregnancy-induced hypertension. If hypertension is accompanied by excess protein in the urine (proteinuria), or swelling (edema) of the limbs or the face (caused by fluid retention), or both, obstetricians refer to it as pre-eclampsia. Proteinuria is usually detected by a dipstick reading at the prenatal visit. Although it is not routinely done, a 24-hour total protein urine test can be performed when the obstetrician wants a more reliable indicator of the problem.
Edema is the least significant indicator of a worsening hypertensive condition, because it is a normal finding in many pregnancies. However, edema of the hands and face is significant when hypertension is present and is accompanied by excessive weight gain.
The signs of elevated blood pressure, proteinuria, and edema are important not only in diagnosing preeclampsia, but also in determining the severity of the disease. Therefore, the patient’s blood pressure, urine, and weight gain should be checked at each prenatal visit. Other clinical findings that indicate a rapidly worsening situation are visual disturbances, ranging from slight blurring to partial or complete blindness; severe headaches; and right upper abdominal pain.
Preeclampsia is life-threatening when several factors combine to produce a condition known as the HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count). Another life-threatening complication, called eclampsia, arises when preeclampsia is accompanied by convulsions (seizures). Either of these may require the prompt delivery of the baby, regardless of the stage of pregnancy, to protect the mother.
There is no cure for preeclampsia other than ending the pregnancy. However, even though adverse maternal consequences usually can be avoided by an early delivery, the baby may be compromised. The obstetrician must balance the benefits to the baby of treating the preeclampsia and prolonging the pregnancy against the risks of growth retardation and asphyxia, as well as the risks to the mother. The doctor must know the baby’s age accurately to know how safe it is to plan an early delivery.
The key questions for a lawyer investigating a birth injury case focus on how the doctor and nurses responded to the testing of the baby and the mother, how good the monitoring was, whether the mother needed early hospitalization or more testing, and how much sense the overall plan made in light of changing circumstances for baby or mother.
Care in the newborn period
Care of a baby who has had asphyxia at birth is vital for preventing further injury and minimizing any injury that has occurred. Some of the goals that are believed to improve the brain outcome of a newborn include:
- Maintaining normal blood sugar,
- Keeping blood pressure normal,
- Preventing or controlling seizures, and
- Preventing or minimizing brain swelling.
In assessing the cause of a baby’s brain injury, it is often important to consult with specialists in pediatric neurology and neonatology to answer whether and to what extent pre-birth or post-birth events contributed to the baby’s injuries.
Legal Consultation
If a family member has suffered a serious, permanent injury related to childbirth, you may want to talk to a lawyer. We provide free consultations to help determine if you have a valid medical negligence case that should be pursued. If you have already consulted with another lawyer or are in the process of doing so, we can offer information about how to evaluate whether you have obtained the right lawyer for your case.
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