Examining the Effects of Prenatal Magnesium Sulfate Exposure on the Risk for Cerebral Palsy in Low Birthweight Children

Background: In 1995, researchers with the California Birth Defects Monitoring Program, Cerebral Palsy Project, reported about an 80% lower prevalence of cerebral palsy among very low birthweight children (<1500 gms) whose mothers had been treated with magnesium sulfate during pregnancy, either for preeclampsia or preterm labor, in comparison with very low birthweight children whose mothers were not treated with the drug.¹ Subsequently, researchers in the Developmental Disabilities Branch also reported an apparent protective effect of prenatal magnesium sulfate exposure on the risk for cerebral palsy or mental retardation among very low birthweight children, based on information obtained through the Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) and the Georgia Very Low Birthweight Study.²These preliminary studies, based on small numbers of children, prompted DDB researchers to conduct the Infant Development Study (IDS) involving a much larger group of children.

Description: The Infant Development Study (IDS) is a case-control study to investigate the apparent protective effect of prenatal magnesium sulfate exposure on the risk for cerebral palsy among low birthweight children. Over 200 children who have cerebral palsy, who were born in the 5-county metropolitan Atlanta area from 1981 through 1989, and who weighed less than 1750 grams at birth, were selected as age subjects for the IDS from MADDSP 1991-92 surveillance records. A sample of over 300 control children born during the same time interval were randomly selected from vital record files of the Georgia Department of Human Resources, on the basis of birth weight and plurality. For each child included in the study, information on selected maternal and infant characteristics was abstracted from the hospital admission and labor and delivery records of the mother and the newborn records of the child.  This information included: maternal treatment with magnesium sulfate and selected other drugs (other tocolytics, steroids and antihypertension medications) during pregnancy; the presence of preeclampsia, hypertension, proteinuria and other maternal medical conditions during pregnancy; characteristics of labor and delivery; and characteristics and medical course of the newborn. The large numbers of affected children included in the IDS will permit researchers to carefully examine many of the factors that might explain why maternal magnesium sulfate treatment during pregnancy appears to protect very low birthweight infants from developing cerebral palsy.

References:

1. Nelson KB, Grether JK. Can magnesium sulfate reduce the risk of cerebral palsy in very low birthweight infants? Pediatrics 1995; 95:263-269. (Abstract)

2. Schendel, DE, CJ Berg, M Yeargin-Allsopp, CA Boyle, P Decouflé. Prenatal magnesium sulfate exposure and the risk for cerebral palsy or mental retardation in very low birthweight children aged 3 to 5 years. JAMA 1996; 276:1805-1810. (Abstract)

Date: October 29, 2005
Content source: National Center on Birth Defects and Developmental Disabilities