The perinatal outcomes of pregnancies with nuchal cord (NC) are uncertain and reports disagree about the incidence of cesarean section due to NC. Variable tightness of the NC may be a contributor to this controversy. The study was to examine whether the tightness of NC affect fetal intrauterine distress by determining valuable ultrasonic indicators. Total 149 singleton pregnancies between 36 and 41 weeks without pregnancy complications were recruited. The pregnant women, whose fetuses have NC, formed the study group and the others made up the control group. The ratio of peak systolic velocity and end diastolic velocity (S/D), pulsatility index (PI) of fetal umbilical artery (UA), middle cerebral artery (MCA) and renal artery (RA) were examed by ultrasound. We found that mean levels of S/D and PI of RA and the incidence of fetal distress and intervention rate during delivery were higher in the study group than those in control group (p<0.05). In contrast, the levels of RI of RA and flow spectrum parameters of UA and MCA showed no difference between the two groups (p>0.05). In addition, as compared with the control group, the mean levels of S/D and PI of RA, S/D of UA were higher in the tight subgroup (p<0.05). The S/D of UA and S/D, PI of RA were increased with D and A1/A, but there were no significant correlations between D or A1/A and fetal distress in study group. In summary, NC affects the level of flow spectrum parameters of RA and UA, especially in tight NC cases, which increases the rate of fetal intrauterine distress. A1/A% and D are valuable ultrasonographic indicator to describe the tightness of NC and predict the fetal hemodynamics, but they could not predict the fetal distress in our study.
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