Mehr Gupta¹, Benjamin Brennan², Amrit Dhanushkoti², Andrew Barker², Adriana E Huelmo², Carl Fayad², Nasser Otutaha², Francis Asence², Carol Wang^2,4, Craig Pennell^2,3,4, Victoria Yachmenikova¹

¹NSW Health Pathology, John Hunter Hospital, Newcastle, Australia; ²School of Medicine and Public Health, College of Health, Medicine and Wellbeing, The University of Newcastle, Newcastle, Australia; ³Department of Maternity and Gynaecology, John Hunter Hospital, Newcastle, Australia; ⁴Mothers and Babies Research Program, Hunter Medical Research Institute, Newcastle, Australia.

 

Background: Mid-trimester pregnancy loss occurs in 0.4-3% of pregnancies. It is poorly understood, with 51% classified as idiopathic. Future pregnancies may be complicated by recurrent mid-trimester loss or preterm birth, and the aetiology/phenotype of the index loss may be predictive of the outcome. This study aims to further characterise the phenotypes of mid-trimester losses and their relationship to future pregnancies by analysing their placental findings. 

Methods: A retrospective cohort study was performed to identify women with mid-trimester losses between 1 January 2013 and 31 December 2023 at John Hunter Hospital.  Mid-trimester was defined as between 14 weeks and 23 weeks and 6 days. Histological reports of each placenta were reviewed and results aggregated. 

Results: A total of 39,331 births were identified, of which 223 (0.59%) resulted in mid-trimester loss in 221 women. The recurrence rate of mid-trimester pregnancy loss was 5.6%, and the rate of subsequent preterm birth was 18.3%. Overall placental findings included acute chorioamnionitis, placental abruption, fetal vascular malperfusion (FVM), maternal vascular malperfusion (MVM), villitis and intervillositis. Placental findings of the index case in those with recurrent losses included chorioamnionitis and villitis. Placental findings of the index case in those with subsequent preterm birth included chorioamnionitis, abruption, FVM, MVM and villitis.