Calls for all pregnant women to be screened for Down syndrome

Dec 8 2008

Experts say Australia needs a national screening policy for Down syndrome as research shows it could halve the number of babies born with the genetic condition.

Currently access to tests that help detect if a foetus has Down syndrome varies widely across states, between urban and rural areas, and public and private patients resulting in stark differences in birth and termination rates.

According to a Danish study a national screening program for expectant mothers significantly reduces the number of babies born with Down syndrome.

The national screening policy for Down’s syndrome was introduced in Denmark during 2004-6 and the research was conducted to evaluate the success of the program.

The researchers from 19 Danish departments of gynaecology and obstetrics hospitals across Denmark found the national screening policy for Down syndrome, increased by 30% the number of babies diagnosed with the syndrome before birth and there were fewer false positives.

The incurable genetic condition occurs in about 2.5 of every 1,000 pregnancies and though the risk increases with maternal age, about half of occurrences are in mothers under 35 with 80% of all mothers in this age group.

The Danish research aimed to measure the number of fetuses and newborn infants with Down’s syndrome diagnosed prenatally and postnatally and found the number of infants born with Down’s syndrome decreased from 55-65 per year during 2000-4 to 31 in 2005 and 32 in 2006.

The researchers say the introduction of a combined risk assessment during the first trimester at a national level in Denmark halved the number of infants born with Down’s syndrome and also resulted in a sharp decline in the number of chorionic villus samplings and amniocenteses carried out, even before full implementation of the policy.

Experts in Australia say every woman should be offered and have access to the best screening tests irrespective of age in general free screening tests are available in public hospital antenatal clinics only to women aged 35 or over or with a family history of chromosomal defects.

According to the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) two screening tests - ultrasound nuchal translucency measurement and serum screening - have a combined detection rate of 90%.

Many experts believe some health policies are out of date and research into births in Queensland between 2000 and 2004 found the incidence of Down syndrome was 56% higher for mothers in the public hospital system than those treated by a private obstetrician possibly because higher income gave access to better-quality testing.

The study also found rural women had a 34% higher risk of having a Down syndrome baby compared with city-dwelling women which illustrates an enormous variation in practice.

The research is published in the current issue of the British Medical Journal.