Chinese University and the Family Planning Association on Thursday said they are launching a free test for couples at risk of having babies with one of about 300 genetic diseases.

Professor Leung Tak-yeung said traditional screening checks could only detect a few conditions, like Down's syndrome, and could only be done during pregnancy or after a baby is born.

The new tests, which determine if people are asymptomatic carriers of a range of genetic disorders, can be carried out even before pregnancy.

“In the past, we needed to test for individual diseases. But now we have an all-in-one test to screen more than 300 genetic diseases in one go,” Leung said.

The new genome sequencing technology called ChromoSeq can also find out if couples have chromosomal issues that can lead to recurrent miscarriages, the professor said.

The test will be offered free of charge at Family Planning Association clinics to couples who have experienced repeated miscarriages, as well as those who have a strong family history of intellectual disabilities.

“We advocate to do the screening test well before pregnancy so that the couples can prepare well before they decide to get pregnant,” Leung said.

The programme, funded by the Jockey Club, could help around 1,000 couples in the next three years.