title: Reducing the risk of fetal distress with sildenafil study (RIDSTRESS): a double-blind randomised control trial.
abstract: BACKGROUND
  Labour is perhaps the most hazardous time in pregnancy. As many as 20 % of cerebral palsy cases in term infants result from intrapartum events and up to 63 % of babies who develop intrapartum compromise have no prior risk factors. Sildenafil citrate (SC), a phosphodiesterase 5 inhibitor, improves uterine blood supply through vasodilatation and potentially could improve placental perfusion and hence reduce the risk of intrapartum fetal hypoxia. The aim of this study is to evaluate the efficacy of SC to reduce the risk of intrapartum fetal compromise and the need for emergency operative delivery.
  
  
  METHODS
  This is a single centre, double-blind, randomised, phase II clinical trial of SC or placebo given during labour to women (18-50 years of age) with a single, appropriately grown, non-anomalous baby at term (37-42 weeks gestation). Those with cardiovascular, renal, hepatic, ocular or hypertensive disease or contraindication to SC will be excluded. Participants will be randomised to either SC 50 mg or placebo capsules eight hourly (SC maximum 150 mg) to commence when admitted to birth suite for management of labour. Within 3 h of the first dose, a repeat ultrasound scan will be performed to measure any changes in uteroplacental and fetal Doppler indices. Labour will continue otherwise in accordance with hospital clinical guidelines. The primary outcome is emergency caesarean section for intrapartum fetal compromise. Secondary outcomes include the effect of SC on fetal and uteroplacental blood flow, meconium liquor, fetal heart rate abnormalities and neonatal outcomes (admission to neonatal intensive care, Apgar <7 at 5 min, cord pH <7.1 or lactate >4.0 mmol/L, neonatal encephalopathy, death).
  
  
  CONCLUSIONS
  This is the first reported study evaluating the efficacy of SC on reducing the risk intrapartum fetal compromise.
  
  
  BACKGROUND
  Australian New Zealand Clinical Trial Registry ACTRN12615000319572.
authors.affiliation: Translating Research Into Practice Centre, Mater Research Institute-University of Queensland, Aubigny Place, Raymond Terrace, South Brisbane, QLD, 4101, Australia. liam.dunn@uqconnect.edu.au.
authors.forename: Liam
authors.initials: L
authors.lastname: Dunn
authors.affiliation: Translating Research Into Practice Centre, Mater Research Institute-University of Queensland, Aubigny Place, Raymond Terrace, South Brisbane, QLD, 4101, Australia. vicki.flenady@mater.uq.edu.au.
authors.forename: Vicki
authors.initials: V
authors.lastname: Flenady
authors.affiliation: Translating Research Into Practice Centre, Mater Research Institute-University of Queensland, Aubigny Place, Raymond Terrace, South Brisbane, QLD, 4101, Australia. sailesh.kumar@mater.uq.edu.au.|School of Medicine, The University of Queensland, Brisbane, Australia. sailesh.kumar@mater.uq.edu.au.
authors.forename: Sailesh
authors.initials: S
authors.lastname: Kumar
mesh_terms: D004311:Double-Blind Method; D005260:Female; D005316:Fetal Distress / Q000188:drug therapy*; D006801:Humans; D011247:Pregnancy; D012307:Risk Factors; D000068677:Sildenafil Citrate / Q000627:therapeutic use*
chemical_list: D000068677:Sildenafil Citrate