Study: Taking Folic Acid In Late Pregnancy May Increase Childhood Allergy Risk

Every pregnant woman knows the significance of folic acid during pregnancy. It is often recommended that women should take folic acid every day starting at least one month before getting pregnant. But, do they need to take it throughout pregnancy? Even though there is no definite answer, a new research says that it may not be necessary.

According to the research, taking folic acid in late pregnancy may increase the risk of allergies in offspring affected by intrauterine growth restriction (IUGR). Intrauterine Growth Restriction is a condition in which a baby does not grow to a normal weight during pregnancy. Several factors like abnormalities in the placenta or maternal medical conditions could contribute to IUGR. The new research, however, suggests that folic acid in late pregnancy may not help babies affected with IUGR.


Understanding Folic Acid

Folic acid, also known as folate, is a B vitamin that is important for pregnant women. It prevents major birth defects of the baby’s brain and spine. It can protect your baby from Neural tube defects (NTDs), which are congenital abnormalities of the brain and spinal column. The neural tube develops in the first weeks of pregnancy. Hence, consuming folic acid in the first trimester is very important. According to the CDC, a woman needs to start taking it at least one month before she becomes pregnant and while she is pregnant. However, the new research does not entertain pregnant women to take folic acid during the late weeks of pregnancy. Let’s see why.

Impact Of Folic Acid In The Last Weeks Of Pregnancy

The research was done by the University of Adelaide’s Robinson Research Institute. The researchers studied lambs born to three groups of sheep.

  • mothers with a smaller-than-normal placenta – “restricted”
  • mothers with a smaller placenta that were also given high doses of a supplement that included folic acid in the last month of gestation – “restricted supplement”
  • mothers with the normal placenta and normal diet – “control”

The researchers exposed them to common allergens – dust mites and egg whites. And they analyzed systemic inflammation and tested skin reactions to these allergens. This is what they found.

The restricted group had higher levels of inflammation when exposed to dust mites. But, there was no difference in skin reaction than the restricted supplement and control groups. However, exposure to egg white protein gave them a different result. The restricted supplement and control groups showed higher rates of allergic reactions than the restricted group. It means that babies of mothers with a smaller-than-normal placenta who have not taken folic acid in the last weeks of pregnancy were not affected by egg white protein like other two groups.


This suggests that folic acid supplementation partially reduced the protection that has previously been seen in pregnancies with restricted growth. Previous studies have suggested that IUGR may have a protective effect against childhood allergies. Now, this research points out that folic acid during the last stages of pregnancy will have a negative effect on this protective effect, thus, increasing the risk of childhood allergies in babies diagnosed with IUGR.

How Much Folic Acid A Woman Needs

Wondering how much of folic acid you require and how long you need to take it? According to the ACOG, before pregnancy and during pregnancy, you need 400 micrograms of folic acid. It is difficult to get folic acid from food alone. So, it is often recommended that pregnant women should take a daily vitamin supplement that contains folic acid.


Well, for how many months? Your health care provider will be the best person to answer that. The researchers behind this study want the doctors to counsel the patients about the potential risks of progeny allergy of continuing folic acid supplementation for the entirety of pregnancy. Talk to your doctor about consuming folic acid supplementation and he/she will be able to give a final verdict, depending on your nutritional requirements.