Copyright restrictions may apply JAMA Pediatrics Journal Club Slides: Peanut or Tree Nut Allergy in Offspring Frazier AL, Camargo CA Jr, Malspeis S, Willett WC, Young MC. Prospective study of peripregnancy consumption of peanuts or tree nuts by mothers and the risk of peanut or tree nut allergy in their offspring. JAMA Pediatrics. Published online December 23, doi: /jamapediatrics

Copyright restrictions may apply Background –The etiology of the increasing prevalence of peanut or tree nut (P/TN) allergy in children is unknown. Study Objective –To examine the association between peripregnancy consumption of P/TN by mothers and the risk of P/TN allergy in their offspring. Introduction

Copyright restrictions may apply Study Design –Prospective cohort study. Setting –United States, in children born between January 1, 1990, and December 31, Patients –Maternal diet was recorded as part of the ongoing Nurses’ Health Study II (n = ). Their offspring are participants in the ongoing Growing Up Today Study 2 (n = ). After exclusions (eg, nonresponse to our 2009 food allergy survey), the analytic cohort comprised 8205 children. Methods

Copyright restrictions may apply Methods Outcomes –Self-report of a physician-diagnosed P/TN allergy, which then was confirmed by medical record review. Limitations –45% of the maternal diets were reported during pregnancy; 76% within 1 year of pregnancy. –Self-reported diagnosis; not food challenge. –History of food allergies in the father were not recorded or accounted for in the analysis.

Copyright restrictions may apply Results Main Study Findings – Authors identified 140 cases of P/TN allergy. – Incidence of P/TN allergy was lower among children of 8059 mothers who consumed more P/TN in their peripregnancy diet (≥5 times vs <1 time per month: odds ratio = 0.31; 95% CI, ; P trend =.004). – In contrast, a nonsignificant positive association was observed in offspring of 146 mothers with P/TN allergy (P trend =.12).

Copyright restrictions may apply Comment Animal studies have shown decreased food allergy in offspring of mothers consuming food allergen during pregnancy and lactation. Human studies have shown inconsistent results, either increased sensitization or no effect. To our knowledge, this is the first human study to indicate that maternal P/TN consumption during the peripregnancy period is associated with reduced P/TN allergy in offspring.

Copyright restrictions may apply Comment Strengths of Study –Maternal history of P/TN consumption was obtained at time of, or within 6 months of, the pregnancy, which improves accuracy of quantitative results relative to recall. –Questionnaires were completed more than a decade before the start of this food allergy study, reducing recall bias that limits retrospective studies. –Recruitment of subjects was not based on atopic history or a genetically high-risk population, increasing the generalizability of study results. –All cases of self-reported physician-diagnosed food allergy were independently reviewed by a board-certified allergist and a board-certified pediatrician. Based on the strength of evidence (medical records, including skin prick and specific IgE test results), confirmation codes were assigned to each case. Our conclusions are likely to be based on true P/TN allergy as opposed to food sensitization alone.

Copyright restrictions may apply Comment Limitations –Dietary questionnaires were not specific for the actual dates of the pregnancy but were chosen closest to the child’s date of birth: 45% were completed during pregnancy; 76% within 1 year of the pregnancy. –The study examined maternal history only; potential paternal effects on the development of P/TN allergy were not investigated. –Potential confounding factors: Mothers consuming more P/TN were more likely to consume more fruits and vegetables (high levels of antioxidants have been associated with decreased atopy) and more likely to introduce P/TN to the child’s diet at an earlier age (may induce oral tolerance). These variables were controlled for in the multivariable models, and they did not materially affect the results.

Copyright restrictions may apply If you have questions, please contact the corresponding author: –Michael C. Young, MD, Division of Immunology, Fegan 6, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA Funding/Support This work was supported by Food Allergy Research and Education, New York, New York. Conflict of Interest Disclosures Dr Young receives royalties from Fair Winds Press for his book titled The Peanut Allergy Answer Book, third edition. No other disclosures were reported. Contact Information