Normal vaginal delivery is defined as a low-risk pregnancy of spontaneous onset of labor taking place between 37 and 42 weeks' gestation, and it is the safest way for the fetus and the mother.
The force caused by the contractile myometrial bundles during labor causes reduction in blood flow with each contraction, as there is a reduction in the placental blood flow causing less efficient gas and nutrient exchange which is detected by the fetus stimulating an increase of heart rate as force getting stronger.
Sildenafil citrate (SC) is potent, selective, and is considered as reversible PDE5 inhibitor which is abundant in the Corpus Cavernosum of the penis and pulmonary arteries. It increases the NO action through PDE5 hindering, resulting in relaxation of smooth muscles and The work was designed to assess sildenafil citrate via different routes versus vaginal placebo to decrease caesarean deliveries due to intra-partum fetal distress depending on the hypothesis that entails that through its vasodilatory action and by increasing uterine and placental perfusion in labor, cervical dilation is enhanced through vasodilation which increases blood flow carrying prostaglandins and hormones acting on cervical tissues, causing more dilatation and effacement, improving myometrium performance which ultimately results in shortening time of delivery and decreasing fetal distress.