Melbourne: Taking folic acid in late pregnancy may increase the risk of allergies in offspring affected by intrauterine growth restriction (IUGR), a study warns.

Folic acid, a type of B vitamin, has been shown to prevent defects in the neural tube – the precursor to the central nervous system – in a developing foetus.


The neural tube develops in the first month of pregnancy; medical professionals typically recommend women take a folic acid supplement during the first trimester of pregnancy.

Continued supplementation, however, may not be needed in the late stages of pregnancy and may actually increase the risk of allergies in offspring.

Researchers at the University of Adelaide in Australia studied lambs born to three groups of sheep: mothers with a smaller-than-normal placenta, 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”).

The third group included mothers with normal placenta and normal diet (“control”).

For the study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, the team measured systemic inflammation and tested skin reactions – markers of allergies – to the common allergens dust mites and egg whites in the lambs.

The restricted group had higher levels of inflammation but no difference in skin reaction than the restricted supplement and control groups when exposed to dust mites.

However, when tested with egg white protein, the restricted supplement and control groups showed higher rates of allergic reaction than the restricted group.

“Patients should be counselled regarding the potential increase risks of progeny allergy of continuing folic acid supplementation for the entirety of pregnancy,” the researchers said.