Prospective Study of Peripregnancy Consumption of Peanuts or Tree Nuts by Mothers and the Risk of Peanut or Tree Nut Allergy in Their Offspring

IMPORTANCE The etiology of the increasing childhood prevalence of peanut or tree nut (P/TN) allergy is unknown. OBJECTIVE To examine the association between peripregnancy consumption of P/TN by mothers and the risk of P/TN allergy in their offspring. DESIGN, SETTING, AND PARTICIPANTS Prospective cohort study. The 10 907 participants in the Growing Up Today Study 2, born between January 1, 1990, and December 31, 1994, are the offspring of women who previously reported their diet during, or shortly before or after, their pregnancy with this child as part of the ongoing Nurses' Health Study II. In 2006, the offspring reported physician-diagnosed food allergy. Mothers were asked to confirm the diagnosis and to provide available medical records and allergy test results. Two board-certified pediatricians, including a board-certified allergist/immunologist, independently reviewed each potential case and assigned a confirmation code (eg, likely food allergy) to each case. Unadjusted and multivariable logistic regression analyses were used to evaluate associations between peripregnancy consumption of P/TN by mothers and incident P/TN allergy in their offspring. EXPOSURE Peripregnancy consumption of P/TN. MAIN OUTCOMES AND MEASURES Physician-diagnosed P/TN allergy in offspring. RESULTS Among 8205 children, we identified 308 cases of food allergy (any food), including 140 cases of P/TN allergy. The incidence of P/TN allergy in the offspring was significantly lower among children of the 8059 nonallergic mothers who consumed more P/TN in their peripregnancy diet (>= 5 times vs <1 time per month: odds ratio = 0.31; 95% CI, 0.13-0.75; P-trend = .004). By contrast, a nonsignificant positive association was observed between maternal peripregnancy P/TN consumption and risk of P/TN allergy in the offspring of 146 P/TN-allergic mothers (P-trend = .12). The interaction between maternal peripregnancy P/TN consumption and maternal P/TN allergy status was statistically significant (P-interaction = .004). CONCLUSIONS AND RELEVANCE Among mothers without P/TN allergy, higher peripregnancy consumption of P/TN was associated with lower risk of P/TN allergy in their offspring. Our study supports the hypothesis that early allergen exposure increases tolerance and lowers risk of childhood food allergy.