Can eating peanuts during pregnancy cause peanut allergy in children?

Peanut allergy is one of the most common allergies in the UK. In England in 2005, it was estimated that around 1 in 2,000 people had a diagnosed peanut allergy. Peanut allergy is known as an IgE-mediated allergy. This means that prior exposure and sensitisation peanuts is required before an allergic reaction is seen. The first time an individual is exposed to peanut, their immune system makes antibodies specific to peanut. This means that if they are exposed to peanut a second time and immune response will occur, this presents as an allergic reaction.

In 1998 the UK government issued some precautionary advice regarding peanut consumption during pregnancy and lactation. Pregnant women with children who had family history of allergic diseases were advised to avoid peanuts during pregnancy and when breastfeeding. They were also advised to avoid giving their child peanuts before they reached 3 years old. This advice stemmed from an increase in the prevalence in peanut allergy which was proposed to be due to more pregnant/breast-feeding women consuming peanuts. It was thought that babies were becoming sensitised to peanuts while in the uterus or due to transmission through the mother’s breast milk.

Evidence supporting this advice is quite conflicting, with some showing an association between maternal peanut consumption and childhood peanut allergy, and some showing no association at all.

A small study conducted in England contradicts the advice issued in 1998. It was found that in 23 children with a peanut allergy there was no evidence of prenatal sensitization through the maternal diet, suggesting that there is no association between maternal peanut consumption during pregnancy and peanut allergy development in their child. However, the study did find that there was an association between the use of skin preparations using peanut oil and the development of peanut allergy.

In a randomised control trial conducted in Canada mothers were split into two groups: the intervention group were instructed to exclude peanuts, other nuts and fish in the last trimester of pregnancy and during lactation, while those in the control group were not. Additionally, cow’s milk, fish and peanuts were excluded from the infant’s diet for the first year of life. No significant difference in peanut sensitization was observed between the children of mothers in the intervention and control group.

In a study published in JAMA Paediatrics studied 8,000 children and how maternal consumption of nuts affected the prevalence of childhood nut allergy. It was concluded that in mothers without nut allergies, consumption of nuts was associated wither lower risk of nut allergy in their offspring. The study suggests that early allergen exposure increases tolerance and reduces the risk of childhood allergy.

It is most commonly reported that children have an allergic reaction on their first known exposure to peanut. This means that sensitisation must have already occurred prior to this. Although this could occur when the baby is in the uterus or through breast-milk, there are other possibilities. These include sensitisation through unintentional consumption of peanut or through respiratory routes.

In 2007 it was concluded by the government that the previously issued advice was no longer appropriate. This lack of clarity can be confusing for mothers to be. A systematic review was conducted in 2017 to summarise all evidence. The recently published SACN report includes the results of this review and states the following:

 

 

  • The available evidence indicates that the deliberate exclusion or delayed introduction of peanut or hen’s egg beyond 6 to 12 months of age may increase the risk of allergy to the same foods.”
  • The available evidence indicates that allergenic foods such as peanut, hen’s egg, gluten or fish can be introduced from around 6 months of age and need not be differentiated from other solid foods.”
  • There is insufficient evidence to demonstrate that the introduction of peanut or hen’s egg into the infant diet before 6 months of age reduces the risk of developing food allergy to any greater extent than introduction from around 6 months of age.”
  • There is insufficient evidence for conclusions to be drawn on the effect of timing of introduction of other allergenic foods in relation to developing an allergy to that food.”

This is the most up to date advice, and takes into account the most recent evidence. As always, it’s talk to a qualified health care professional if you have any questions or worries.

 

Hannah is a Final Year Nutrition student at the University of Nottingham, who aspires to go on a study a Masters in Dietetics. Her interests include nutrition education and maternal and child health. Follow her on Twitter at @hlj_jones