A new report by the all-party House of Lords science and technology committee, due out on Wednesday, is expected to withdraw the warning.
The committee, which has been investigating the rise of allergies in the UK, has been considering evidence which shows that there is a much lower incidence of peanut allergy in countries where babies are exposed to them early in life.
In Israel and some African countries, where babies are weaned on groundnut soup, the committee heard that there is little or no peanut allergy in the population.
The current Department of Health advice, dating from 1998, states that pregnant women should avoid eating peanuts if they or their baby's father, or a sibling, suffers eczema, hayfever or asthma, because they may have a higher risk of developing a nut allergy.
It suggests these mothers should delay introducing peanuts into their children's diet until the age of three.
It is understood ministers now believe this advice could be counter-productive and that delaying introducing nuts into young children's diets could, on the contrary, be fuelling the rise in allergies in the UK.