Research articleEvaluation of changes in Doppler ultrasonography indices and levels of maternal serum angiogenic factors throughout pregnancy in ewes

We evaluated the changes in the pulsatility index (PI) and resistance index (RI) of fetal and maternal vessels and maternal serum angiogenic factors throughout pregnancy in 20 Kivircik ewes. They were examined for pregnancy detection on Day 30 after mating. The PI and RI during the pregnancies were followed using Doppler ultrasonography (USG) of the uterine artery, umbilical artery, fetal aorta, and fetal vena cava. Doppler USG was performed every 15 days beginning from the 40th day after mating. Blood samples were collected every 15 days starting from the day of mating. Nitric oxide (NO), vascular endothelial growth factor, basic fibroblast growth factor, and angiopoietin-1 and -2 levels were measured in maternal serum. A gradual decline was observed in the PI and RI of the umbilical artery beginning from Day 75 of pregnancy. Similarly, the RI of the uterine artery decreased on Day 135. Embryonic resorption was detected in two ewes with an increased PI and RI in the uterine artery. A significant and gradual decrease in the maternal serum vascular endothelial growth factor level was observed throughout pregnancy. The maternal serum NO level increased beginning from Day 135 of pregnancy. The results of this study illustrate the progressive changes in the Doppler USG findings of fetomaternal vessels and maternal serum angiogenic factors that occur throughout ewe pregnancy. The umbilical and uterine artery Doppler USG findings and maternal serum NO concentration may be important parameters for evaluation of the course of pregnancy in ewes. The results of this study should be compared with those of further studies that include compromised pregnancies and nonpregnant ewes.