To investigate whether maternal anxiety in the third trimester is associated with an increased uterine artery resistance index. Cohort based study. 100 pregnant women, with a mean gestation of 32 weeks. Self rating Spielberger questionnaire for state anxiety and trait anxiety, and uterine blood flow waveform patterns as assessed by colour Doppler ultrasound. A significant association was found between uterine artery resistance index and scores for both Spielberger state anxiety and trait anxiety (rs=0.31, P<0.002 and 0.28 P<0.005 respectively). Women with state anxiety scores >40 (n=15) had a higher mean uterine resistance index than those with scores 40 (n=32) had a higher mean resistance index than those with scores