Cerebral Palsy Risks & Pregnancy
Cerebral palsy (CP), a group of chronic disorders characterized by impaired body movement and a loss of motor muscle control, currently affects more than 500,000 Americans. Each year approximately 4,500 American infants are diagnosed with cerebral palsy. Symptoms of CP may include shaking of limbs, loss of balance, inability to walk, seizures, and delay in growth and development. The disorder may also be linked to learning disabilities and mental retardation.
Although CP can be caused by an infection in the first month of life or by an injury in early childhood, most cases are congenital, or present at birth, and their cause is unknown. Through research, however, scientists have pinpointed some specific events during pregnancy or around the time of birth that can damage motor centers in the developing brain and increase the risk of CP. For example, infections that affect the mother during pregnancy such as rubella, cytomegalovirus, or toxoplasmosis may affect the fetus in the uterus, causing brain damage.
Research scientists have also uncovered certain characteristics, called risk factors, that increase the possibility that a child will later be diagnosed with CP. One risk factor is low birth weight or premature birth; the risk of CP is higher among babies who weigh less than 2,500 grams (5 lbs., 71/2 oz.) at birth and among babies who are born less than 37 weeks into pregnancy.
Another risk factor is the existence of a maternal disorder such as hyperthyroidism (overactive thyroid), mental retardation, or seizures; mothers with any of these conditions are slightly more likely to have a child with CP than those without such conditions.
A healthy pregnancy, which can be achieved through regular prenatal care, good nutrition, and elimination of smoking, alcohol consumption, and drug abuse, should be the goal of every pregnant woman and her physician.
The National Institute of Neurological Disorders and Stroke (NINDS) conducts and supports research aimed at preventing CP. Much of this research focuses on discovering ways to lower the risk of CP during pregnancy and identifying and learning more about risk factors for the disorder. Three NINDS-supported studies are reported below.
Magnesium Sulfate and Decreased Risk of CPIn a study conducted by NINDS and the California Birth Defects Monitoring Program, investigators found that very low birth weight babies have a decreased incidence of CP when their mothers are treated with magnesium sulfate soon before giving birth.
Low birth weight babies are 100 times more likely to develop CP than normal birth weight infants. Magnesium is a natural compound responsible for numerous chemical processes within the body and brain. Obstetricians often administer magnesium sulfate, an inexpensive form of the compound, to pregnant women to prevent preterm labor and high blood pressure brought on by pregnancy. The drug, administered intravenously in the hospital, is considered safe when given under medical supervision.
"Electronic monitoring provides an up-to-the-minute
check of the fetus's health. When an irregular
heartbeat is detected — which may be a sign of too
little oxygen — doctors often perform an emergency
cesarean section in an effort to prevent brain
damage that can result in CP or mental retardation."
The investigators concluded that magnesium sulfate helps reduce the risk of CP in very low birth weight infants. Despite these encouraging research findings, scientists warn, pregnant women should not change their magnesium intake. More research will be required to establish a definitive relationship between the drug and prevention of CP.
Neonatal Thyroid Function and CPIn another study, scientists have linked low levels of a thyroid hormone in premature infants to the development of CP. The investigators examined more than 400 premature infants screened for blood levels of the hormone thyroxine during the first week of life and found that infants with low levels of thyroxine at birth had an increased incidence of CP at age 2.
The study, funded by NINDS and the National Institute of Child Health and Human Development, is the most comprehensive exploration of the relationship between low levels of thyroid hormone (a condition called hypothyroxinemia) at birth and neurodevelopment in premature infants. Premature infants often go through a period of transient hypothyroxinemia. In most cases, including those in which CP is indicated, thyroid function returns to normal within a few weeks or months.
Although this finding raises optimism that the risk of CP in children can be reduced, more research is needed to determine if treatment with thyroid hormone will prevent abnormalities in prenatal brain development that lead to CP.
Fetal Monitoring and Risk of CPRecently, in a large study funded by NINDS, investigators found that electronic fetal heartbeat monitoring during delivery is not helpful in preventing CP and may lead to a higher rate of potentially dangerous cesarean sections.
Electronic monitoring provides an up-to-the-minute check of the fetus's health. When an irregular heartbeat is detected — which may be a sign of too little oxygen — doctors often perform an emergency cesarean section in an effort to prevent brain damage that can result in CP or mental retardation.
Results from the study revealed that of every 100,000 babies monitored during birth, 9,300 will have abnormal heartbeats. Yet just 18 of these babies will be expected to have CP. Due to the false alarms, however, many of the 9,300 mothers will be rushed to the operating room for cesarean sections. About 4 percent of these operations will result in serious complications for the mother, such as bleeding and infection. The researchers concluded that in most cases electronic monitoring may be more risky than beneficial.
Further, the researchers found that performing a cesarean section does not prevent CP. Among the babies who had ominous signs during monitoring, those delivered by cesarean section did not have a lower frequency of CP than those delivered vaginally.
These findings reinforce other research, discussed earlier, showing that most CP cases can be traced to events such as maternal infections early in pregnancy that may damage the fetus' central nervous system.
Research conducted and supported by NINDS continuously seeks to uncover new clues about CP. As investigators learn more about the causes of CP through basic and clinical research, doctors and parents will be better equipped to help prevent this disorder. The ultimate hope for overcoming CP lies with prevention.
DiSCLAIMER: The content of this site is offered as educational material for parents, not as medical advice. If you have a question about a specific condition or symptom your child has then you need to consult a medical professional.