Table 1 Characteristics of included studies/trials
Study | Methods | Location | Treatment group, N | Sildenafil dose, mg | Control group, N | Gestational age at randomization | Primary outcome |
|---|---|---|---|---|---|---|---|
Abdelshafy et al., 2019 [27] | Randomized, double -blind, placebo-controlled trial | Egypt | N = 45 | 25 mg tid until delivery | Placebo, N = 45 | Between 24–34 weeks of gestation | The pulsatility index (PI) of the umbilical artery (UA) before and after treatment |
El-Sayed et al., 2017 [14] | Randomized, double -blind, placebo-controlled trial | Egypt | N = 27 | 50 mg of single dose until delivery | Placebo, N = 27 | At < 24 weeks of gestation | Doppler changes (PI, RI and S/D ratio) in MCA, uterine, and umbilical arteries |
El-Shalakany et al., 2018 [15] | Prospective randomized, placebo-controlled trial | Egypt | N = 40 | 25 mg 3/day until delivery | Placebo, N = 40 | Between 24- 34 gestation weeks | Length of pregnancy, neonatal weight, ICU admission |
Eshraghi et al., 2021 [28] | Randomized, double -blind controlled trial | Iran | N = 40 | 25 mg daily | 40 | Above 28 weeks of gestation | Fetal weight, abdominal circumference, PI, and RI of the umbilical and cerebral arteries, and S/D of the umbilical artery |
Groom et al., 2019 [29] | Randomized, triple-blind, placebo-controlled trial | New Zealand, Australia | N = 63 | 25 mg tid from randomization until 32 weeks of gestation, delivery or fetal death | Placebo, N = 59 | between 22 weeks 0 days and 29 weeks 6 days of gestation | proportion of pregnancies with an increase in fetal growth velocity |
Pels et al., 2020 [30] | Randomized, placebo-controlled trial | Netherlands | N = 108 | 25 mg tid from randomization until 32 weeks of gestation, delivery or fetal death | Placebo, N = 107 | Between 20 weeks 0 days and 27 weeks 6 days | perinatal mortality or major neonatal morbidity before the neonate was discharged from the hospital |
Sharp et al., 2018 [18] | Randomized, placebo-controlled, double -blind trial | UK | N = 70 | 25 mg tid until 32 weeks of gestation or delivery | Placebo, N = 65 | Between 22 and 29 weeks and 6 days of gestation | Pregnancy prolongation from randomization till delivery |
Shehata et al., 2018 [32] | Randomized, double -blind, placebo-controlled, trial | Egypt | N = 23 | 20 mg tid | Placebo, N = 23 | Between 24–34 weeks of gestation | uteroplacental perfusion improvement, increase in abdominal circumference growth velocity after randomization |
Trapani et al., 2016 [31] | Randomized, double -blind, placebo-controlled, trial | Brazil | N = 50 | 50 mg sildenafil citrate every 8 h | Placebo, N = 50 | Between 24–33 weeks of gestation | Pregnancy prolongation from randomization till delivery |