Comparison of alterations in fetal regional arterial vascular resistance in appropriate-for-gestational-age singleton, twin and triplet pregnancies.

The objective of this longitudinal study was to evaluate alterations in fetal vascular resistance of fetal peripheral arteries with advancing gestation in singleton appropriate-for-gestational-age (S-AGA), twin appropriate-for-gestational-age (Tw-AGA) and triplet appropriate-for-gestational-age (Tri-AGA) infants. Colour Doppler flow imaging and pulsed Doppler ultrasonographic examinations were performed on 35 S-AGA, 52 Tw-AGA and 12 Tri-AGA fetuses. The pulsatility index for middle cerebral artery (MCAPI), umbilical artery (UAPI), descending aorta (DAPI), splenic artery (SAPI), renal artery (RAPI) and femoral artery (FAPI) was measured as vascular resistance every 2 weeks after 15 weeks of menstrual age until delivery. Optimal models and normal ranges for pulsatility index for each artery in each group were generated. The alterations in various fetal regional arterial pulsatility indices with advancing gestational age showed no significant differences in S-AGA, Tw-AGA and Tri-AGA infants, respectively. These results suggest that there is no significant difference for regional arterial vascular resistance in AGA fetuses among singleton, twin, and triplet pregnancies, whereas there was a slight difference in fetal growth pattern among singleton, twin, and triplet pregnancies described in our previous investigation.