Sydney (IANS): Younger women are more likely to have neural tube defect (NTD) affected pregnancies than older women, according to a new study.

The report showed that teenage women had the highest rate of NTD affected pregnancies and women aged 30-34 years the lowest. The neural tube becomes the brain and spinal cord.

"Multiple pregnancies were also more likely to have neural tube defects than singleton pregnancies," said Samanthi Abeywardana of the Australian Institute of Health and Welfare's (AIHW) National Perinatal Statistics Unit.

"During last three decades, mounting evidence has shown that increased intake of folic acid during the period around conception corresponds with a decreased prevalence of neural tube defects," Abeywardana said.

Neural tube defects are major congenital anomalies that result from very early disruption in the development of the brain and spinal cord. Surviving children are at high risk of frequent illnesses, disability and death, according to a release of AIHW.

Spina bifida is the most commonly known neural tube defect.

"In light of this evidence Australia will join many other developed countries in implementing mandatory folic acid fortification of bread making flour (from September 2009) to minimise the births affected with neural tube defects," Abeywardana said.

Although there is only about one NTD-affected birth per 2,000 births, the estimated prevalence of NTDs among pregnancies is much higher, at more than one per 1,000, because some women diagnosed with NTD-affected pregnancies opt for planned termination.