Fetal response to maternally administered morphine

OBJECTIVE: We sought to determine the effects of maternally administered mo rphine on fetal response. STUDY DESIGN: Singleton pregnancies requiring fetal blood sampling were enr olled. Only study patients were given morphine intramuscularly. Maternal vi tal signs, fetal heart rate, biophysical profile score, and umbilical arter y Doppler indices (systolic/diastolic ratio, resistance index, and pulsatil ity index) were completed before and after fetal blood sampling. Maternal a nd cord blood morphine concentrations were measured. RESULTS: Ten study and 6 control patients were enrolled. A significantly lo wer biophysical profile score was observed in study patients (P = .001) as a result of absent fetal breathing movements and nonreactive nonstress test s. Gross and fine fetal movements were unaffected. A significant correlatio n was measured between the biophase morphine concentration and each of the Doppler indices. CONCLUSION: Morphine administered to the mother causes a significant decrea se in the biophysical profile score. Correlation between the biophase morph ine concentration and the Doppler indices was calculated. These results sug gest that morphine acts as a vasoconstrictor of the placental vasculature b ut do not support the use of intramuscular morphine to suppress fetal movem ent.