Pregnancy test could identify complications

Causes of pregnancy complications including miscarriage and foetal death may soon be identified through a new screening test.

Researchers from Victorian Clinical Genetics Services at the Murdoch Childrens Research Institute and Illumina’s Northern California Services Laboratory have developed a method to allow women to gain greater insights into the health of their pregnancy, in the biggest study of its type in the world.

Pregnant women can already access a non-invasive prenatal test (NIPT), which is a highly accurate method for screening chromosome conditions such as Down syndrome. This research is looking at the possibility of expanding this blood test to check for other important health concerns caused by other chromosome conditions.

Lead author Dr Mark Pertile, head of reproductive genetics at Victorian Clinical Genetics Services, said the study could help women be better informed about the health and progress of their pregnancy.

“Expanding NIPT to include all chromosomes can provide women with additional information about the health of their pregnancy,” Dr Pertile said.

The new study published in Science Translational Medicine looked at nearly 90,000 pregnancies from two clinical laboratories in Australia and the USA, which both identified similar frequencies of rare trisomies using NIPT.

Down syndrome, also known as trisomy 21, is caused by an extra copy of chromosome number 21, where there are three copies of chromosome 21 instead of the usual two. Current NIPT methods only test for the most common trisomies, which includes only 3–5 chromosomes out of the 24 possible types that can be tested.

This study expanded the NIPT test to look at all 24 chromosomes, and showed that missing or extra copies of these chromosomes can result in serious pregnancy complications. 

“We thought that by analysing whole genome sequencing data from all chromosomes, we might find a way of identifying rare autosomal trisomies to improve the understanding of fetoplacental biology,” co-author Dr Meredith Halks-Miller said.

Data showed that rare trisomies were often associated with serious pregnancy complications including miscarriage, foetal growth restriction and spontaneous foetal death. In some cases, only the placenta was affected by the rare trisomy and not the baby, but this could still cause serious problems for the normal development of the pregnancy.

During pregnancy, small fragments of genetic material pass from the placenta into the mother’s bloodstream. This genetic material can be tested using NIPT to provide important information on the health of pregnancy.

“This may help doctors in monitoring pregnancies at increased risk for complications such as foetal growth restriction and may also provide a reason for why some pregnancies have miscarried,” Dr Pertile said.

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