It is our pleasure to see your interest in our article published in the Green Journal.1 You have addressed pregnancy-associated cardiovascular changes and the possible consequences or risks when intravenous fluid hydration was considered to improve oligohydramnios as in our study; namely, pulmonary edema, especially in woman with a high risk, such as preeclamptic women. In our study, to avoid such risk, we adopted two policies. Firstly, all women with predisposing medical factors such as kidney, heart, or lung diseases were excluded. Secondly, during the hospitalization stage, maternal monitoring was done for early detection of any manifestations of fluid overload. There is increasing evidence that the heart rate may be the most important means of raising fetal cardiac output, which is based on experimental animal physiology studies as highlighted by Kiserud and Acharya in their review article.2
The obstetrician has a difficult mission to care for two patients: a “hidden” one kept in a visible one, so he is obliged to provide dual care! Given the proposed cardiac hemodynamic mechanisms in our hidden patient, which you have focused on with possible maternal hemodynamic changes, fetal monitoring during the hospitalization stage for our study participants was implemented to monitor for possible abnormal fetal cardiac activity patterns during intravenous hydration, whether with or without the added sildenafil citrate.
Studies have shown improvement in uteroplacental Doppler parameters in pregnancies complicated by intrauterine growth restriction.3,4 However, no clear data exist concerning the effect of sildenafil on human fetal central hemodynamics and whether they are the same or not for both growth-restricted and normally growing fetuses, although one animal experimental study has shown lowered central fetal hemodynamics during induced hypoxemia in a sheep model.5 Owing to lack of clear evidence of a deleterious effect of oral sildenafil on human fetal hemodynamics, electronic fetal monitoring of the study participants outside the hospital was during clinic follow-up. Further studies are warranted to explore the effect of sildenafil citrate on amniotic fluid volume under different circumstances.