A randomised controlled trial of sildenafil therapy to improve the growth of babies in the womb

Dr Katie Groom
University of Auckland 

What is the problem and who does it affect?

Intrauterine growth restriction (IUGR) is a term used to characterise poor growth of a baby in a mother’s womb. It affects approximately 10% of all pregnancies, some of which need very early delivery before 32 weeks’ gestation. Tragically, it can also be a contributing cause of stillbirth.

We know that very preterm birth as well as growth restriction can subject babies to numerous short and long-term adverse health outcomes, including cerebral palsy and hypertension.

IUGR is characterised by placental insufficiency, more specifically, a lack of oxygen and nutrients reach the baby through the placenta, which can cause their growth to slow. The only available treatment is for an obstetrician to plan an early birth. As mentioned above, the adverse health outcomes associated with very early birth are numerous, and hence, it is imperative that treatments be found to improve growth and wellbeing in the womb, enabling better health outcomes for these babies.


What is this project hoping to achieve?

Dr Katie Groom is the lead investigator of the multicentre STRIDER NZAus Trial which is using sildenafil as a treatment to try and promote growth of babies in the womb. IUGR is routinely caused by reduced placental blood flow, whereas, sildenafil has the effect of vasodilation; expanding the blood vessels and increasing blood flow. There are several examples of pre-clinical evidence showing dilation of the utero-placental arteries.

Last year, Cure Kids funding supported a Clinical Trial Manager to oversee the completion of recruitment as well as to support the planning of an essential, longer-term follow up of recruited mothers.

Cure Kids are pleased to once again be supporting this study. The objective of this specific grant is to now follow up those babies given sildenafil as treatment as well as those receiving placebo, to assess whether any benefit or harm accrues to these babies as result of treatment. Children at 2-3 years-of-age will be assessed against a number of metrics including neurodevelopmental, respiratory and cardiovascular problems, and hospital visits among others.

Data from this trial will be combined with that of other similar trials across the world working in the STRIDER Collaboration, and may be sufficient to conclusively show that sildenafil not only improves the survival rate of vulnerable growth-restricted babies, but also improves longer-term life outcomes.