Sildenafil Citrate for the Management of Asymmetrical Intrauterine Growth Restriction
Status:
Unknown status
Trial end date:
2017-04-01
Target enrollment:
Participant gender:
Summary
Intrauterine growth restriction (IUGR) is defined as fetal abdominal circumference (AC) or
estimated fetal weight (EFW) < 10th centile. In asymmetrical IUGR the parameter classically
affected is the abdominal circumference (AC). Fetal growth restriction (FGR) complicates
approximately 0.4% of pregnancies and severely increases the risk of perinatal morbidity and
mortality. This is particularly due to premature delivery, both for fetal and for secondary
maternal indications such as the development of pre-eclampsia.
Consequence of deficient uteroplacental blood flow, including IUGR, pre-eclampsia, and
placental abruption have been implicated in more than 50% of iatrogenic premature births. For
this reason, the problem of severe IUGR forms a substantial portion of the population that
tertiary care centres care for.
The effect of early-onset IUGR is particularly significant: of those born alive, less than a
third will survive their neonatal intensive care unit (NICU) stay without significant
neurodevelopmental sequelae. Survival rates for severely growth-restricted fetuses very
remote from term (<28 weeks' gestation) vary from 7% to 33%.
As these early-onset IUGR children are born very preterm, there are significant risks of
neonatal mortality, major and minor morbidity, and long-term health sequelae.
The use of ultrasound Doppler waveform analysis in pregnancies complicated by IUGR suggests
compromised uteroplacental circulation and placental hypoperfusion. Currently there are no
specific evidence-based therapies for placental insufficiency and severe IUGR. Non-specific
interventions include primarily lifestyle modifications, such as reducing or stopping work,
stopping aerobic exercise, rest at home, and hospital admission for rest and surveillance.
These interventions, which are not supported by evidence from randomized trials, are used in
the belief that rest will enhance the uteroplacental circulation at the expense of that to
the glutei and quadriceps muscles.
There is evidence from ex vivo and animal models of growth restriction that the
phosphodiesterase 5 inhibitor sildenafil citrate increases average birth weight and improves
uteroplacental blood flow (umbilical artery, uterine artery).