A new screening test could help expecting parents find causes for serious pregnancy complications including miscarriage and fetal death.

Researchers from the Victorian Clinical Genetics Services at the Murdoch Children’s 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 the Victorian Clinical Genetics Services, Murdoch Children's Research Institute, 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 to 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 analyzing whole genome sequencing data from all chromosomes, we might find a way of identifying rare autosomal trisomies to improve the understanding of feto-placental biology,” co-author Dr Meredith Halks-Miller formally Laboratory Director at Illumina’s Northern California Services Laboratory, now at GRAIL, Inc. said.

Data showed that rare trisomies were often associated with serious pregnancy complications including miscarriage, fetal growth restriction and spontaneous fetal 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 fetal growth restriction and may also provide a reason for why some pregnancies have miscarried,” Dr Pertile said.