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.