Cytomegalovirus (CMV) is the most common cause of congenital infection, with approximately 0.5% of pregnant women being infected during pregnancy. CMV transmission to the fetus occurs in about one third of women who are infected in first trimester. Babies infected before birth are at risk for serious neurological complications such as intellectual disability, seizures, deafness, and even death. Most couples facing a diagnosis of congenital cytomegalovirus infection in their unborn baby focus heavily on the predicted neurological outcome for their child. To date, methods to assess brain development in fetuses have been mainly limited to detecting structural brain abnormalities by ultrasound. However, these ultrasound signs may not become apparent until very late in pregnancy, and some neurological disability is not accompanied by any structural brain changes. More research on methods of predicting neurodevelopmental outcome independent of structural brain malformations before third trimester is urgently needed.
The purpose of this study is to investigate a new method of studying the health of unborn babies using amniotic fluid. Amniocentesis is often performed after maternal CMV infection to diagnose fetal infection. Prior research by Dr Hui has demonstrated that cell free RNA in amniotic fluid can provide meaningful information from multiple organs including the fetal brain. The investigators propose to collect and analyse a small sample of amniotic fluid to detect which genes are turned “on” or “off” (gene expression) in a fetus that has a congenital CMV infection, compared to those without any infection.
The genes that are differentially expressed in CMV infected fetuses will then be analysed to provide information on the broad physiological processes that are altered due to the infection (“functional analysis”) and identify neurodevelopmental gene transcripts of interest for future studies (“biomarker discovery”).