For release: Wednesday, February 8, 1995A new study shows that very low birthweight babies have a lower incidence of cerebral palsy (CP) when their mothers are treated with magnesium sulfate soon before giving birth. The findings come from a study sponsored by the California Birth Defects Monitoring Program (CBDMP) and the National Institute of Neurological Disorders and Stroke (NINDS) and reported in the February 1995 issue of Pediatrics .*
The study compared a group of 42 very low birthweight children who had moderate or severe congenital CP to a control group of 75 very low birthweight children without the disability. Three of the 42 mothers of children with CP and 29 of the 75 mothers of children in the control group received magnesium sulfate during pregnancy. The researchers concluded that magnesium sulfate seems to have a protective effect against CP in very low birthweight infants.
The investigators caution however that more research will be required to establish a definitive relationship between the drug and prevention of the disorder. The current study results are based on observations of a group of children born in four northern California counties.
"This intriguing finding means that use of a simple medication could significantly decrease the incidence of cerebral palsy and prevent lifelong disability and suffering for thousands of Americans," said Zach W. Hall, Ph.D., director of NINDS.
CP is a serious disorder that causes problems in movement control in more than half a million Americans at an estimated cost of $5 billion a year. Many people with CP suffer additional neurological disabilities, including mental retardation and epilepsy. More than 25 percent of all CP occurs in very low birthweight babies, defined as those born weighing less than 1500 grams, or 3.3 pounds. There are approximately 52,000 very low birthweight babies born each year. Of these, one in 20 who survives infancy has CP.
"Although medicine has made striking advances in allowing more preterm babies to survive, some of these children face grievous, lifelong disabilities. We hope the findings from our study will help prevent cerebral palsy in some of these vulnerable infants," said Karin B. Nelson, M.D., acting chief of the NINDS neuroepidemiology section and lead author of the paper. She added that very low birthweight babies are 100 times more likely to have disabling CP than infants of the most common birthweight (3000-3500 grams).
Magnesium sulfate, an inexpensive natural chemical, is commonly used in the United States by obstetricians to prevent preterm labor or to treat preeclampsia, high blood pressure brought on by pregnancy. The drug, which is delivered intravenously in the hospital, is considered relatively safe when given under medical supervision.
The beneficial effect of the magnesium sulfate seen in this study was similar whether the mothers received the drug for convulsions associated with preeclampsia or for preterm labor. The investigators also found that magnesium sulfate appeared to confer a protective effect against CP whether or not the mothers received other drugs to stop preterm labor or to enhance fetal lung maturation in premature infants.
Dr. Nelson and co-author Judith K. Grether, Ph.D., of the CBDMP, have not yet compiled data on the exact dosages of magnesium sulfate administered or on the time of treatment relative to the time of birth. This information is important since it takes 2 to 3 hours for magnesium sulfate to reach the fetus.
"Based on our work, other scientists are already looking at their data and seeing similar associations," said Dr. Grether. "If these are confirmed in clinical trials, we will be able to learn even more about the usefulness of magnesium in premature birth."
The study authors speculate that magnesium may play a role in brain development and possibly prevent cerebral hemorrhage in preterm infants. Although the precise mechanism for this effect is not known, several suggestions for effectiveness can be cited. An earlier study has shown higher survival rates in infants born weighing less than 1000 grams whose mothers were given magnesium sulfate; and in animal models magnesium has been associated with decreased brain injury after the brain has been deprived of oxygen.
Magnesium is an essential part of the diet and is found in green vegetables, beans, meat and chocolate.
The CBDMP was established by the state of California in 1982 to collect and analyze data on children with birth defects, and since that time has accumulated records on hundreds of thousands of children.
NINDS, one of the National Institutes of Health located in Bethesda, MD, is the nation's principal supporter of research on the brain and nervous system. The Institute is a lead agency for the Congressionally designated Decade of the Brain.
*Karin B. Nelson, M.D.; Judith K. Grether, Ph.D. "Can Magnesium Sulfate Reduce the Risk of Cerebral Palsy in Very Low Birthweight Infants?" Pediatrics, February, 1995, Vol. 95, Number 2, p. 263.
Last Modified August 7, 2009