The effect of magnesium sulfate tocolysis on the fetal biophysical profile

Alan M. Peaceman, Bruce A. Meyer, James A. Thorp, Valerie M. Parisi, Robert K. Creasy

Research output: Contribution to journalArticle

32 Scopus citations


The biophysical profile has proved to be a valuable tool for the assessment of fetal well-being, independent of gestational age. Magnesium sulfate is commonly used as a tocolytic agent, yet relatively little is known about its effects on the biophysical activities of the fetus. To investigate the effects of magnesium sulfate on the biophysical profile, we performed serial studies on patients who received tocolytic therapy with this agent because of preterm labor. A total of 16 women with 22 fetuses at 26 to 34 weeks' gestation in spontaneous preterm labor were studied. An initial biophysical profile was performed at the time of admission, and a second examination was performed when maternal serum magnesium levels reached 6 to 8 mg/dl. On admission all fetuses had reactive nonstress test results and 21 of 22 (95%) demonstrated sustained fetal breathing movements. With magnesium sulfate tocolysis, 50% of fetuses had nonreactive nonstress test results, and only 4 of 22 (18%) demonstrated sustained fetal breathing movements. Fetal tone, gross body movements, and amniotic fluid volume were found to be unaffected by magnesium sulfate tocolysis.

Original languageEnglish (US)
Pages (from-to)771-774
Number of pages4
JournalAmerican journal of obstetrics and gynecology
Issue number3
StatePublished - Sep 1989



  • Magnesium sulfate
  • biophysical profile
  • preterm labor

ASJC Scopus subject areas

  • Obstetrics and Gynecology

Cite this