Fetal response to maternally administered morphine.

OBJECTIVE

We sought to determine the effects of maternally administered morphine on fetal response.

STUDY

DESIGN

Singleton pregnancies requiring fetal blood sampling were enrolled. Only study patients were given morphine intramuscularly. Maternal vital signs, fetal heart rate, biophysical profile score, and umbilical artery Doppler indices (systolic/diastolic ratio, resistance index, and pulsatility index) were completed before and after fetal blood sampling. Maternal and cord blood morphine concentrations were measured.

RESULTS

Ten study and 6 control patients were enrolled. A significantly lower biophysical profile score was observed in study patients (P =.001) as a result of absent fetal breathing movements and nonreactive nonstress tests. Gross and fine fetal movements were unaffected. A significant correlation was measured between the biophase morphine concentration and each of the Doppler indices.

CONCLUSION

Morphine administered to the mother causes a significant decrease in the biophysical profile score. Correlation between the biophase morphine concentration and the Doppler indices was calculated. These results suggest that morphine acts as a vasoconstrictor of the placental vasculature but do not support the use of intramuscular morphine to suppress fetal movement.