Trials are underway in Melbourne of a possible new blood test for mothers, which can check for changing oxygen levels in utero.

Researchers have been assessing the link between an RNA substance in a mother’s blood and the oxygen level of her baby.

Dr Claire Whitehead, lead author of a new study, says the team is working on a new, non-invasive test to determine foetal oxygen levels before birth.

Currently ultrasound is employed as a common technique for investigating the health of an unborn baby. The inverse link between levels of the specific RNA fragments in blood samples and oxygen in babies could add a new dimension to the vital assessments.

In small-scale trials so far, blood samples were taken from 20-women with pre-term babies as well as 30 carrying healthy babies.

Tests are being ramped-up to include seven hospitals at locations around the world.

Findings so far have been published in the journal BMC Medicine.