Uterine Artery Doppler Changes After Vaginal Administration of Isosorbide Mononitrate In Patients With Unexplained Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is an important reproductive health issue, because it affects 2%-5% of couples. The incidence of RPL varies widely because of the differences in the definitions and criteria used, as well as the populations characteristics (El Hachem et al., 2017).

The reported incidence of early pregnancy loss depends on the method used to detect pregnancy. An estimated 50% of all conceptions are lost at preclinical stages owing to biochemical loss or implantation failure, further 9-20% of clinically recognized pregnancies are miscarried, mainly during the first trimester (weeks 5-12 of gestation), studies consistently demonstrate a sharp reduction after 12 weeks of gestation to an incidence of ~1% suggesting that most pregnancy losses occur soon after implantation (Dimitriadis et al., 2020).

The Royal College of Obstetricians and Gynecologists defines RPL as three or more consecutive pregnancy losses, The most recent RPL guideline from European Society of Human Reproduction and Embryology states that RPL could be considered after the loss of two or more pregnancies and stresses the importance of the need for further scientific research, including epidemiological studies on the effect of various RPL definitions on diagnosis, prognosis and treatment (ESHRE 2017).

Common established causes include uterine anomalies, antiphospholipid syndrome, hormonal and metabolic disorders, and cytogenetic abnormalities. Other etiologies have been proposed but are still considered controversial, such as chronic endometritis, inherited thrombophilia, luteal phase deficiency, and high sperm DNA fragmentation levels (Yang et al., 2019).

Over the years, evidence-based treatments such as surgical correction of uterine anomalies or aspirin and heparin for antiphospholipid syndrome have improved the outcomes for couples with recurrent pregnancy loss. However, almost half of the cases remain unexplained and are empirically treated using progesterone supplementation, anticoagulation, and/or immunomodulatory treatments. Regardless of the cause, the long-term prognosis of couples with recurrent pregnancy loss is good, and most eventually achieve a healthy live birth. However, multiple pregnancy losses can have a significant psychological toll on affected couples, and many efforts are being made to improve treatments and decrease the time needed to achieve a successful pregnancy (El Hachem et al., 2017).