AMNIOTIC-FLUID NITRIC-OXIDE AND UTEROPLACENTAL BLOOD-FLOW IN PREGNANCY COMPLICATED BY INTRAUTERINE GROWTH-RETARDATION

Objective To examine the correlation between placental nitric oxide pr oduction and uteroplacental blood flow. Participants Thirty-one pregna nt women with fetuses with intrauterine growth retardation and 27 norm al pregnancies as controls. Design Correlation between amniotic fluid measurements of nitrite metabolite in the third trimester and flow vel ocimetry waveforms recorded from uterine, umbilical and fetal middle c erebral arteries. Intrauterine growth retarded pregnancies were compar ed with controls. Main outcome measures Concentrations of nitric oxide metabolites (NO2- and NO3-) in amniotic fluid were correlated with fl ow velocimetry waveforms findings by the determination of correlation coefficient. Results Overall median nitrite values in amniotic fluid w ere higher (P < 0.01) in intrauterine growth retarded patients (median 8.6 mu mol/mg creatinine) than in controls (5.6 mu mol/mg creatinine) . Pathologic uterine flow velocimetry waveforms in uterine artery (-2S D) were observed in 12 women of the intrauterine growth retarded group , and the concentration of amniotic fluid nitrite was significantly lo wer (P < 0.01) in these patients (median 4.45 mu mol/mg creatinine) th an in those with normal flow velocity waveforms (median 11.43 mu mol/m g creatinine). A significant negative correlation was observed between nitrite concentrations and uterine artery resistance index, umbilical artery pulsatility index and umbilical artery pulsatility index:middl e cerebral artery pulsatility index ratio. Conclusions We conclude tha t placental nitric oxide is significantly associated with uteroplacent al blood flow and may be important in maintaining adequate uteroplacen tal perfusion in intrauterine growth retarded pregnancies.