Folic acid is found in broccoli
Taking folic acid before pregnancy could reduce the risk of the baby having Down's syndrome, researchers have suggested.
It has been known for some time that folic acid, found in foods such as broccoli or in supplements, protected against neural-tube defects.
Researchers have now shown that children born to families with a high risk of neural-tube defects could also be at an increased risk of Down's syndrome and vice versa, suggesting there is a link between the two conditions.
They suggest a dose of five milligrams of folic acid could reduce the risk of Down's syndrome as well as cutting the likelihood of a baby having a neural-tube defect (NTD).
NTDs are the abnormal development of the neural tube, which becomes the brain or spinal cord, in early pregnancy.
Anencephaly, the partial or complete absence of the brain, and spina bifida are the most severe NTDs, causing serious physical and mental impairment.
Problems in metabolising folic acid have been seen in mothers of babies with NTDs.
It has also been suggested it could be a risk factor for trisomy 21, the chromosomal abnormality which causes Down's syndrome.
An international team of researchers studied 493 Israeli families who had had a previous pregnancy which was affected by NTD and 516 families from the Ukraine who had had a pregnancy affected by Down's.
Their findings were published in The Lancet.
It was found there were more than five times the number of pregnancies affected by Down's syndrome, a total of 11 in 1,492 pregnancies in the NTD compared with 1.87 expected for women of the same age.
There was also an increase in NTD cases in the families at a higher risk of Down's syndrome.
Seven cases were seen in 1,847 pregnancies, compared with an expected incidence of 1.37.
Writing in The Lancet, the researchers from Israel, the Ukraine and the UK recommended taking extra folic acid before conception, and in the first two months of pregnancy.
They added: "The risks seen in this study could be helpful in genetic counselling, including that given during antenatal screening for birth defects.
Professor Howard Cuckle of Leeds Antenatal Screening Service and the International Down's Syndrome Screening Group, worked on the study.
He said: "This provides direct evidence of a link between Down's syndrome and NTD.
"Folate supplementation before conception has the potential to reduce the frequency of Down's syndrome."
Writing in an editorial in The Lancet, Dr Jørgen Olsen and Jeanette Falck said: "Although the report is somewhat provocative, it may well be the first epidemiological indication of the existence of a mechanism which could be used at a later stage in the primary prevention of Down's syndrome."
A spokeswoman for the Down's Syndrome Association said: "There is currently very little understanding of why babies are born with Down's syndrome, so any research that sheds light on the causes of the condition would be of interest.
"This study delivers no real answers but it presents some directions for future research."
But she added: "It is important to remember that babies with Down's syndrome will always be born and that all existing and future people with DS should receive the support they need to fulfil their individual potential.
"Parents of children with DS should understand that they are not at fault and that nothing they did or failed to do caused their child to be born with the condition."
High blood pressure
A second study has suggested high blood pressure problems in pregnancy, including pre-eclampsia increases a woman's risk of heart disease in later life.
The study in the British Medical Journal found those who had experienced raised blood pressure in pregnancy had a long-term risk of hypertension (high blood pressure), an increased risk of stroke and a slightly increased risk of heart disease.
The long-term risks were highest for women with pre-eclampsia.
The researchers, from the University of Aberdeen, said: "Women with a history of gestational hypertension or of pre-eclampsia or eclampsia are at increased risk of hypertensive and associated diseases in later life."
They said if there was a greater awareness of the link, it could lead to earlier diagnosis and better management of patients, potentially reducing the numbers made ill or killed by such diseases.