OC01.02: The assessment of microRNA expression in pregnancies classified as a pregnancy of unknown location using transvaginal ultrasonography

Abstract

Objectives: To evaluate if SC compared to placebo reduced the incidence of operative intervention for IFC in term pregnancies. Methods: This was a double blind placebo controlled pilot RCT and was conducted at the Mater Mother’s Hospital in Brisbane, Australia between 2015 and 2018. The primary outcome was the difference in operative intervention (Caesarean or instrumental birth) rates for presumed IFC. Participants received either SC (50mg 8 hourly) or placebo during labour. Women with term, singleton pregnancies with normally grown fetuses were included. The study was not powered to detect differences in neonatal outcomes. We also analysed maternal Placental Growth Factor (PlGF) levels before and after treatment in a sub group of women to ascertain if SC influenced intrapartum placental function. Results: 300 women were randomised to either SC or placebo. SC reduced the odds of operative delivery for IFC by 62.0% (18.0% vs. 36.7%; OR 0.38, 95% CI 0.22-0.65; NNT = 5, 95%CI 3-11). It also reduced the odds of emergency Caesarean by 56.0% (10.0% vs. 20.0%; OR 0.44, 95% CI 0.28-0.87; NNT = 10, 95% CI 6-50) and of instrumental vaginal birth for IFC by 57.0% (8.0% vs. 16.7%; OR 0.43, 95% CI 0.21-0.90; NNT = 12, 95% CI 6-76). The overall spontaneous vaginal birth rate increased from 43.3% to 54.0%. Pathological fetal heart rate patterns, intrapartum fetal blood sampling and meconium stained liquor rates were lower in the SC cohort. SC administration did not reduce the incidence of any of the pre-specified adverse perinatal outcomes. There was a greater decline in PlGF levels in the placebo cohort [-11.7 (-22.6 – 1.0) pg/mL] compared to the sildenafil group [1.2 (-29.2 – 23.4) pg/mL] post-treatment [Percentage change: SC +3.99 (-18.2-41.4) % vs Placebo -14.4 (-29.1 – 1.4) % vs, p < 0.05]. For women with a pre-treatment PlGF of > 85 pg/ml and <397mg/ml, SC significantly reduced the risk of operative delivery for IFC. Conclusions: Oral SC in labour reduces operative birth for IFC at term.