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.

Reference:

• Caesarean births not linked to increased risk of food allergy during infancy. https://www.mcri.edu.au/news/caesarean-births-not-linked-increased-risk-food-allergy-during-infancy. Posted May 19, 2022. Accessed May 19, 2022.

PERSPECTIVE

BACK TO TOP 

Tetsuhiro Sakihara, MD

The authors demonstrated that elective or emergency cesarean delivery with or without labor was not associated with the risk for food allergy development at age 12 months in HealthNuts cohort participants. One of the strengths of this study was its use of OFC tests to confirm food allergies.

Although there was no significant difference, infants born through vaginal delivery had a higher proportion of egg allergy development compared with those born through cesarean delivery in this study. On the other hand, the proportion of peanut allergy development was higher in those born through cesarean delivery compared with those born through vaginal delivery.

Our nested case-control trial of SPADE study participants also demonstrated that only a proportion of hen’s egg sensitization development at 6 months of age was higher among infants born through vaginal delivery compared with those born through cesarean delivery. The effect of delivery mode on the development of food allergy might differ between food allergens.

In addition, although there were no significant differences, the authors demonstrated that cesarean delivery with labor had higher proportions of egg allergy and peanut allergy development compared with cesarean delivery without labor. Our analysis revealed that participants who developed food sensitization had longer labor durations than those without food sensitization. Furthermore, longer labor durations were significantly associated with a higher proportion of participants with food sensitization.

Several reports have indicated that cesarean delivery can elevate the risk for food sensitization and food allergy compared with vaginal delivery. However, our study and Currell and colleagues showed that cesarean delivery might not elevate the risk for food sensitization and food allergy.

Several important potential confounders such as indication of cesarean delivery, labor duration, levels of stress hormone and microbiota should be considered in future research.