Background: The purpose of the current study was to compare the color Dop-pler findings of uterine arteries and perinatal outcomes in pregnant women with and without previous cesarean section (C/S).
Methods: This cohort study enrolled 308 pregnant women aged 20-35 without underlying diseases, with at least one previous pregnancy and childbirth. The participants were divided into two groups: 154 women without C/S and 154 women with C/S. Baseline data were collected, followed by uterine artery Dop-pler scans. Then, the perinatal outcomes, including pre-eclampsia, intrauterine growth restriction (IUGR), premature delivery, and birth weight were evaluated.
Results: The average age of patients in the C/S group was 30.46±3.81, which was significantly higher than the non-C/S group (28.86±4.64). It was found that uterine artery resistance was higher in women with C/S history (1.11±0.44, p<0.001) compared to those without (1.00±0.37, p<0.001). Pre-eclampsia inci-dence was also higher in C/S group (16.1%, p=0.042) compared to non-C/S group (9.1%, p=0.042). The incidence of preterm birth in the C/S group (p=0.209), the incidence of IUGR (p=0.791), and the average birth weight (p=0.291) in the two groups did not differ significantly.  The average gestational age in the C/S group was 37.54±1.4, and in the non-C/S group was 38.01±1.99 weeks. The results were not affected by potential confounders such as age, the time interval between pregnancies, and also body mass index.
Conclusion: Previous cesarean section can significantly increase the uterine ar-tery resistance in subsequent pregnancy.