The efficacy of sildenafil therapy in dismal prognosis early-onset intrauterine growth restriction: the STRIDER RCTScientific summaryChapter 1. IntroductionChapter 2. ObjectivesChapter 3. MethodsChapter 4. ResultsChapter 5. DiscussionChapter 6. Summary of key findingsAdditional informationReferencesAppendix 1List of abbreviations