Relationship between prepregnancy and early pregnancy uterine blood flow and resistance index.

We evaluated the relationship between prepregnancy and early pregnancy uterine blood flow (UBF) and resistance index (RI). Nineteen nulliparous participants were studied during cycle day 8 + 4, and early pregnancy (13.4 + 1.6 weeks). Color Doppler ultrasound of both uterine arteries and maternal heart was performed to calculate uterine RI, volumetric UBF, and cardiac output (CO), respectively. We observed a strong negative association of uterine RI with prepregnancy UBF (r = -.82, P < .001) that weakened, but remained significant in early pregnancy (r =-.48, P = .04). Prepregnancy uterine index (UBF/CO) was significantly associated with early pregnancy uterine index; r = .48, P = .04). There was also a trend associating prepregnancy and early pregnancy volumetric UBF (r = .44, P = .068). Prepregnancy UBF may be a determinant of early pregnancy UBF and UBF may have independent value as a predictor of adverse pregnancy outcome.