Whether infants were born via vaginal or cesarean delivery did not lead to meaningful differences in likelihood of food allergy at age 12 months, according to a study published in The Journal of Allergy and Clinical Immunology.
The lack of likelihood persisted regardless of onset of labor or whether cesarean deliveries were elected or emergent, Anne Currell, MEpi, a researcher in population health at Murdoch Children’s Research Institute in Parkville, Victoria, Australia, and colleagues wrote.
The researchers examined 2,045 infants born between September 2007 and August 2011 in the Melbourne area from the HealthNuts population-based longitudinal study, where parents completed questionnaires and infants underwent skin prick testing, oral food challenges and blood collection.
Of the included infants, 70% were delivered vaginally, 12.5% were born by cesarean section after the onset of labor and 17.5% were born by cesarean section before the onset of labor. Also, 14.9% of births were emergency cesarean sections, and 15.2% were elective cesarean sections.
Overall, 13% of infants were sensitized to food and 18.7% had food allergy.
Food allergy occurred among 12.7% of infants born via cesarean delivery and 13.2% of those born vaginally, indicating no evidence of an association between type of delivery and risk for any food allergy (adjusted OR = 0.95; 95% CI, 0.7-1.3), including to egg (aOR = 0.8; 95% CI, 0.57-1.13) or peanut (aOR = 1.11; 95% CI, 0.69-1.91).
However, food allergy occurred among more children born by cesarean section after labor had started (14.2%) than those born vaginally (13.3%) or via cesarean without labor (11%), but adjusted models showed no association between labor and risk for any food allergy, including egg or peanut allergy.
Fewer infants born via emergency cesarean section experienced food allergy (11.2%) than those born via elective cesarean section (13.4%) or vaginal delivery (13.3%), but adjusted models indicating no risk for any food allergy — egg or peanut included — based on these qualifications.
The researchers additionally found no evidence for increased risks for food allergy based on breastfeeding, older siblings, a pet dog or maternal history of allergy, with similar results for egg and peanut allergies.
Similarly, the researchers continued, there was no evidence of an association between mode of cesarean birth (with or without labor, or elective or emergency cesarean) and risk for food, egg or peanut sensitization compared with vaginal delivery.
The researchers noted the microbial exposure hypothesis, which proposes that altered exposure to microbes and infections early in life could predispose infants to allergic disease, with mode of delivery potentially influencing the microbiome.
However, the researchers wrote, their results suggest that gut colonization may begin in utero and have an impact on the infant’s microbiome and on risks for allergic disease, not just mode of delivery.
Caregivers can consider these findings, the researchers continued, in advising patients about the benefits and risks that come with cesarean delivery and in reassuring them that their infants are not likely to be at increased risk for food allergy.