In a study on Danish mothers, the children of those who ate peanuts and nuts while pregnant were less likely to develop asthma or allergies than the kids whose mothers shunned nuts.
The results support the recent withdrawal of recommendations that pregnant women should avoid nuts because they might raise a child's risk for allergies to the nuts themselves and for other hypersensitivities like asthma, according to the US and Danish researchers.
"There's some mixed data out there and this current study is showing that maybe there might be a benefit to your child in having less asthma later on if you continue to just eat the way you're still eating and not avoid [nuts]," said Dr Todd Mahr, a pediatric allergist at Gundersen Lutheran Medical Centre in La Crosse, Wisconsin, who was not involved in the study.
In 2008, the American Academy of Pediatrics rescinded its recommendation that women should avoid eating peanuts while pregnant to prevent a possible food allergy, and the UK's health agency did the same in 2010.
There is little research implicating even peanuts, specifically, eaten by a pregnant mother and her child's risk for peanut allergy - much less a wider range of sensitivities. Yet the fear continues to lead many expectant mothers to steer clear of nuts.
So Ekaterina Maslova, a researcher at the Centre for Fetal Programming at Statens Serum Institut in Copenhagen, wanted to take a more extensive look at nut exposure and the possible health outcomes in kids.
Maslova's team, who published their results in The Journal of Allergy and Clinical Immunology, collected survey responses from more than 61,908 Danish moms who gave birth between 1996 and 2002, and analysed their kids' medical records at the ages of 18 months and seven years old.
The mothers had provided information about how often they ate peanuts and tree nuts, such as almonds and walnuts, during pregnancy.
At age 18 months, the researchers found, the kids whose mothers ate peanuts were less likely to have asthma.
Fifteen per cent of kids whose moms ate peanuts more than once a week, for instance, had asthma compared to more than 17 per cent of kids whose moms never ate peanuts.
When other asthma risk factors were taken into account, the researchers concluded that kids whose mothers ate peanuts regularly were 21 per cent less likely to develop asthma.
At seven years old, this same group of kids was 34 per cent less likely to have a diagnosis of asthma than kids whose moms had abstained from peanuts.
Similarly, mothers who ate tree nuts more than once a week had 18-month-olds who were 25 per cent less likely to have asthma and wheeze than the moms who avoided the nuts, although this difference appeared to fade as the kids reached seven years old.
Peanuts appeared to have no effect on whether kids developed nasal allergies, and the children of moms who frequently ate tree nuts were 20 per cent less likely to have allergies.