Lesson 5: Folic Acid Epidemiology Studies, Excite, Folic Acid, NCBDDD, CDC

Researchers have found that the B-vitamin, folic acid, can prevent neural tube defects like anencephaly and spina bifida. As a result, there is something women can do to prevent many of these birth defects from happening in the future.

A study was done in Europe, and the results were published in 1991. Women who had already had a baby with an NTD were given a pill to take before their next pregnancy and during the first 3 months of pregnancy (first trimester). One group was given extra folic acid. The second group was given a pill without folic acid. None of the women or their doctors knew which type of pill they were taking. Below is a table of the results of the study.

Study of women who had already had a baby with an NTD
	With NTD	Without NTD	Total	Percent with NTD
Group 1 Folic Acid	6	497	593	6 ÷ 593 x 100 = 1%
Group 2 No Folic Acid	21	581	602	21 ÷ 602 x 100 = 3.5%

In epidemiology, we calculate relative risk to show the difference from one treatment to another.

RELATIVE RISK A comparison of the risk of disease in one group with the risk of disease in another group.

Divide the risk of having a baby with an NTD without taking folic acid into the risk of having a baby with an NTD when taking folic acid.

The study found the risk for having a baby with an NTD is 3.5 times higher if a woman did not take folic acid. It appeared that folic acid protected women from having another baby with an NTD.

As a result of the study, the CDC made a statement in its August 2, 1991, Morbidity and Mortality Weekly Report (MMWR). The MMWR is a weekly report of illnesses and deaths in the U. S. published by CDC in Atlanta. This statement urges women who already had a baby with an NTD and are planning to have another baby to take 4 milligrams (mg) of folic acid. They should start taking 4 milligrams of folic acid before they get pregnant and during the first 3 months of pregnancy (first trimester).

Another research study testing folic acid was published in 1992. This study focused on women who had not had a baby with an NTD. All of these women were given one of two pills to take before they were pregnant and through the first trimester. One group took folic acid with other vitamins (a multivitamin). The second group received a different pill without folic acid. Once again, none of the women knew what type of pill they were taking.

Study of women who had not had a baby with an NTD before
	With NTD	Without NTD	Total	Percent with NTD
Group 1 Folic Acid	0	2,104	2,104	0 ÷ 2104 x 100 = 0%
Group 2 No folic Acid	6	2046	2052	6 ÷ 2052 x 100 = 0.3%

None of the women who took folic acid in a multivitamin had a baby with an NTD. Three out of 1000 women (0.3%) who did not take folic acid had a baby with an NTD. Thus, NTD risk was greater in the group that didn't take folic acid.

Calculate and interpret the relative risk for this example. A study in the U. S. followed women who had never had a baby with an NTD. Women who took a pill with folic acid before pregnancy and during the first trimester were compared with women who did not take vitamin pills during this time.

Study of women who had not had a baby with an NTD before
	With NTD	Without NTD	Total	Percent with NTD
Group 1 Folic Acid	10	10,703	10,713	10 ÷ 10713 x 100 = 0.093%
Group 2 No folic Acid	39	11,905	11,944	39 ÷ 11944 x 100 = 0.325%

0.325 ÷ 0.093 = about 3.49 times greater risk of having a baby with an NTD
As a result of this study, the U. S. Public Health Service announced on September 11, 1992, that all women who could possibly get pregnant should take 0.4 milligram of folic acid every day.

1 Gram = 1,000 milligrams = 1,000,000 micrograms. A gram is about the weight (but not the size) of two raisins, so a microgram is a very, very small amount. Because we need only a small amount of folic acid, it is called a micronutrient. Still, folic acid is very important every day because the body has to have it for healthy blood and cells and to make DNA.

The word microgram can also be shown as mcg or µg. The Greek symbol µ means micro and is pronounced mu. The word milligram can be shown as mg. Both milligrams and micrograms are used to describe the amount of folic acid in food.

The U. S. Public Health Service recommends that all women who can become pregnant take 0.4 mg of folic acid. The recommendation also states that women who have already had a baby with an NTD and want to have another baby should take 4 milligrams of folic acid daily.

Find the amount of micrograms (mcg) equal to 4 milligrams (mg) of folic acid.
Hint: 1 mg = 1000 mcg.

How many micrograms of folic acid do women who have already had a baby with an NTD need to reduce the chance of having another baby with an NTD? (Answer: 4000 micrograms)

The U. S. Public Health Service announced in 1992, that all women who could get pregnant should take 0.4 milligram of folic acid every day. Using the metric system, convert 0.4 milligram (mg) into micrograms (mcg or µg). Hint: 1 mg = 1000 mcg.

How many micrograms (mcg) of folic acid do women who have not had a baby with an NTD need a day? (Answer: 400 mcg)

Who needs to take more folic acid: women who have already had a baby with an NTD or women who have not had a baby with an NTD? How much more folic acid do they need? Why do you think they need more?

Women who have already had a baby with an NTD and want to have another baby should take more folic acid. If they have already had one baby with an NTD, they are more likely to have another with the birth defect. Therefore, they need to take 10 times as much, 4000 mcg folic acid instead of 400 mcg. People who take more than 1000 mcg of folic acid should only take it under the care of a doctor.