To the Editor.
—The article by Dr Schendel and colleagues1 may have more methodologic limitations than the authors acknowledge. Perhaps the major limitation is the failure to recognize that magnesium might be a marker for other phenomena that contribute to reduced risk of cerebral palsy.During the years study subjects were born (1986-1988), magnesium sulfate was not used as a first-line tocolytic. From 1984 through 1987,31% of the 90 women in one Boston, Mass, hospital who received magnesium sulfate just prior to the birth of a very low-birth-weight infant had a diagnosis of pregnancy-induced hypertension or preeclampsia recorded in the hospital chart,2 similar to the experience in Atlanta, Ga reported by Schendel et al.1 On interview, however, approximately 31% of these women acknowledged that they were told they had either preeclampsia or hypertension.If the situation in Atlanta mimicked what we found in Boston, then receipt of
Allred EN, Dammann O, Kuban KKC, Leviton A, Pagano M, Stewart JE, VanMarter LJ. Prenatal Magnesium Sulfate Exposure and Risk of Cerebral Palsy. JAMA. 1997;277(13):1033. doi:10.1001/jama.1997.03540370023015