INTRODUCTION
miscarriages, unexplained recurrent pregnancy loss, uterine artery blood flow
UTERUS, MISCARRIAGES, MISCARRIAGE, RECURRENT MISCARRIAGE, RECURRENT PREGNANCY LOSS, RECURRENT MISCARRIAGES, PATHOLOGY, ANEUPLOIDY
Endometrial thickness and uterine blood flow influence pregnancy continuation until term. Nifedipine, a type II calcium channel blocker, and Sildenafil, a type 5-specific phosphodiesterase inhibitor, have shown the potential to improve these factors. This study aims to compare the safety and efficacy of Nifedipine and Sildenafil in improving endometrial blood flow and thickness in Iraqi women with recurrent first-trimester miscarriages. Women with unexplained recurrent pregnancy loss in the first trimester (non-pregnant during the study) were randomly assigned to two groups. Transvaginal color Doppler ultrasound assessed uterine artery pulsatility, resistance indexes, and endometrial thickness during the second phase of the menstrual cycle (day 15 to day 25). The first group received oral Nifedipine (10 mg) twice daily, while the second group received oral Sildenafil citrate (20 mg) every 8 hours from day 5 to day 25. Baseline measurements showed no significant differences in pulsatility index between the groups (2.02±0.52 for Nifedipine, 2.03±0.49 for Sildenafil, p=0.927). Sildenafil treatment resulted in a more noticeable reduction in the pulsatility index. The resistive index had a significant difference in baseline readings (0.98±0.14 for Nifedipine, 1.06±0.14 for Sildenafil, p=0.033), with Sildenafil showing a more pronounced reduction. Post-treatment, Sildenafil demonstrated a greater improvement in endometrial thickness than Nifedipine (10.09±0.74 mm Recurrent pregnancy loss is a significant reproductive challenge, and its definition varies across countries. In the United States, it is characterized by failed clinical pregnancies in two or more consecutive attempts, with documentation based on histopathology and/or ultrasound [Unexplained recurrent miscarriage represents three or more miscarriages in healthy women without any known underlying pathology. However, research suggests that a subset of women with unexplained recurrent miscarriages may have underlying pathologies contributing to their condition. As a result, there are two categories of unexplained recurrent miscarriages: type I, which happens by chance in females without an obvious pathology and the prognosis of such type, is good, and type II, which is associated with an undetected pathology not routinely identified by clinical methods and tends to have a poorer prognosis [The etiology can be attributed to genetic abnormalities such as aneuploidy [The prevalence rate of recurrent pregnancy loss is much lower than spontaneous miscarriage [A competent blastocyst and a receptive uterus interact during the highly coordinated implantation process. Natural reproductive ability in humans indicates that implantation failure accounts for about two-thirds of lost pregnancies and that the chance of conception every cycle is relatively modest (30%). Optimum uterine artery blood flow and endometrial thickness are essential for successful implantation [Two important factors that may affect the continuation of pregnancy until term are endometrial thickness and uterine blood flow [This research aimed to compare the safety and efficacy of Nifedipine 