Alpha Plus Or Triple Screening

A new test may help you decide whether you need amniocentesis.

A single blood test can measure three biochemical markers; alpha fetal protein, estriol and human chorionic gonadotropin. The results of these tests as well as a blood test for diabetes, and the mother's age, pregnancy dates, weight, are fed into a computer, which can then print out the calculated risk for Down's Syndrome and other related genetic abnormalities. If the calculated risk is as high as that of a woman 35 or over, amniocentesis will then be offered to a younger woman. If a woman is over 35, she can also get an estimate of how high her risk for these problems is.

In July 1993 the province of Ontario started a province wide screening program to assess the usefulness of this test as part of the prenatal work-up.

Dr. Anne Summers, a clinical geneticist at North York General Hospital in Toronto, told the Medical Post (Nov 3/93) that the new test will be able to diagnose Down's in 70 percent of the cases overall and in 80 percent of women over 35. It can also pick up about 70 percent of neural tube defects. Dr. Summers feels it gives women over 35 another choice. "If the results show relatively little chance of a Down's Syndrome baby they may decide against amniocentesis."

Folic Acid Can Prevent Structural Birth Defects

Defects where the skull bone doesn't form over the spinal chord or brain, (neural tube defect or NTD) affect 300,000 to 400,000 infants per year worldwide, with 2,500 to 3,000 per year in the United States, and 800 in Canada. In Canada, the incidence of NTD is about one in 1,000 births. If a woman has already had a child with this problem the incidence is 20 per 1,000. There is now compelling evidence that taking folic acid supplements can reduce the incidence of this serious problem by at least 50 percent.

A 1989 study in Boston, involving 23,000 women, showed that women who took multivitamins containing folic acid during the first six weeks of pregnancy had the lowest risk of delivering a baby with NTD, compared with women who took multivitamins without folic acid, and those starting multivitamins with folic acid after seven weeks of pregnancy.

In 1991, the Lancet medical journal reported on a large well-designed study of 1,195 women at high risk for having an NTD, (because of a previous baby who had the problem) conducted by the Medical Research Council of Great Britain, at 33 centers in seven different countries, including Canada and the United States. The study showed that women who took 4mg of folic acid daily for the first 12 weeks of pregnancy were able to prevent 72 percent of neural tube defects, compared to women in the same high risk group who didn't take this supplement.

Most recently, in the December 1992 issue of the New England Journal of Medicine, a large, well designed study of 4,000 pregnancies in Hungary provided even more convincing evidence that taking multivitamin supplements containing at least .8mg of folic could prevent NTD in women who did not have a history of a previous problem.

As a result of these and other studies, in March 1993, the Society of Obstetricians and Gynecologists of Canada (SOGC), recommended that doctors advise all women of child bearing age to take supplements containing .4mg of folic acid supplements or the dietary equivalent, according to the food rules. During pregnancy, supplements should contain at least 0.8 to 1.0mg folic acid per tablet.

An alternative approach suggested by the SOGC is for all women of child bearing age to take .4mg folic acid or the dietary equivalent, starting immediately after they stop using birth control, until at least ten to 12 weeks after a missed period.

Women who have already had a baby with NTD and women at high risk for NTD should consider taking 4mg of folic acid daily after discontinuing birth control until ten to 12 weeks after a missed period.

Folic acid is present in dark green leafy vegetables, brewer's yeast, whole grains, legumes and organ meats. Folic acid is very sensitive to heat, light and any type of cooking. Since low doses of folic acid supplements are very safe, it is probably wisest to use supplements as well as diet to get adequate amounts of folic acid.