OBJECTIVE The authors aimed to determine and compare the uterine artery pulsatility index (PI) between spontaneous and IVF twins in the second trimester. METHODS All medical records of twin pregnancies, whose fetal screening was done between May 1999 and December 2013, were evaluated retrospectively. All twin pregnancies without detected/suspicious anatomical or genetic fetal anomalies, systemic diseases, biochemical abnormalities, and familial genetic diseases were included in the data analyses. Fetuses with no information on spontaneous or IVF conception and fetuses with undetermined uterine artery impedance of second trimester were excluded from the data analyses. RESULTS A total of 151 twin pregnancies were evaluated in the analyses. The percentages of spontaneous and IVF twins were 24.5% and 75.5%, respectively. Mean gestational age was 19.95 ± 2.25 weeks in IVF twin group and 20.10 ± 2.19 weeks in spontaneous twin group. The difference of the gestational age between groups was not statistically significant. Mean uterine artery impedance was found as 0.78 ± 0.22 in IVF twins and 0.96 ± 0.31 in spontaneous twins respectively). Mean values were significantly lower in the IVF twins (p = 0.09). CONCLUSIONS The uterine artery PI in the second trimester is significantly lower in IVF twins compared to the spontaneous twins.