Are Cesarean sections linked to food allergies?

Children’s Allergy Research Group Survey Notes

Birth Mode Links to Allergy

June 2014

Members of the Research Group were asked to complete a short questionnaire about each of their children with regards to their mode of birth and the atopic conditions they suffer from.

We were interested in testing the popular theory that there is an increased incidence of allergy in women who have cesarean sections and incidence of allergy.

Results

We had 100 respondents to the survey, with only 1 void response.  These 99 responses represent 99 children.  Of these children there were 54 male and 45 female.  91 children suffer from allergies or other related atopic conditions and 8 children did not (our control group).

Mode of Birth

Mode of Birth No. Of Children
Normal Vaginal Birth 56
Cesarean (First) 32
Cesarean (Repeat) 9
Vaginal Birth after

C- Section (VBAC)

2

Conditions Suffered

Condition No. of Children Comments
Food Allergy 75 38% female, 62% male

54% V, 36% C, 7% RC, 3% VBAC

Eczema 59 42% female, 58% male

54% V, 34% C, 9% RC, 3% VBAC

Hayfever 51 31% female, 69% male

63% V, 25% C, 8% RC, 4% VBAC

Asthma 40 34% female, 66% male

68% V, 20% C, 7% RC, 5% VBAC

Other Environmental Allergy* 33 36% female, 64% male

58% V, 27% C, 9% RC, 6% VBAC

Food Intolerance 30 37% female, 63% male

50% V, 36% C, 7% RC, 7% VBAC

Allergic Asthma** 27 30% female, 70% male

52% V, 37% C, 4% RC, 7% VBAC

Eosinophilic Disorders 3 33% female, 67% male

33% V, 33% C, 33% RC

CONTROL (no atopic conditions) 8 75% female, 25% male

63% V, 37% C

* excluding pollen but inclusive of allergy to dust mites, animal dander etc.
** asthma as a symptom of an allergic reaction

Notes

The cesarean rate in our group was 41.4% compared to 26.2% in the general UK population (NCT maternity statistics 2013/14).

8 of the children were controls as they did not suffer from any of the atopic conditions looked at in the survey.  Of the other 91 children, most suffered from multiple atopic conditions, with only 11 having to contend with one condition (80 dealing with multiple atopic conditions).

There were 23 children surveyed who had showed classic ‘Allergic March’ (or AM where they have eczema, food allergy/intolerance, hayfever AND asthma), so almost a quarter of the group, of these 15 were born vaginally, 5 by cesarean, 1 by repeat cesarean and 2 by VBAC.

As there were only 2 VBAC children and they suffered from 4 or more atopic conditions no conclusions can really be drawn about this mode of delivery due to the small sample size.

The 3 children with eosinophilic disorders all suffered from various conditions and had different modes of delivery, again this was a small sample size so no conclusions can be drawn from this information.

Interestingly there was a higher rate of males suffering from atopic conditions in all categories.  In the control group of those not suffering from any of our atopic categories there were more females.

Conclusions

There is a commonly held theory that babies born by cesarean have a higher incidence of allergies as they are born in  a more sterilised environment and are not exposed to necessary microbiota as those born vaginally (sometimes known as the hygiene hypothesis).

I was surprised, I expected a clear link between cesarean and allergy and there wasn’t one.  I also expected our results to contradict those of large research studies, but if you take a look at the selection of studies below our survey matched those previously undertaken in that our results were inconclusive, there is not enough evidence for a strong link between birth mode and incidence of allergy, but we also saw that there seemed to be more boys than girls suffering from atopic conditions.

Further Reading

A retrospective chart review to identify perinatal factors associated with food allergies, Nutritional Journal, 2012, 11:87

http://www.biomedcentral.com/content/pdf/1475-2891-11-87.pdf

Study of 291 children, no link to cesarean section to be associated with increased risk of food allergy diagnosis

Delivery by Cesarean Section Increases Risk for Food Sensitization At Age 2 Years, The Journal of Allergy and Clinical Immunology, February 2013, Vol 131

http://www.jacionline.org/article/S0091-6749(12)02761-3/fulltext

Study of 572 children, link between c sections and allergy when mother was atopic.

Caesarean section and allergic manifestations: insufficient evidence of association found in population-based study of children aged 1 to 4 years, August 2013, Volume 102:10

http://onlinelibrary.wiley.com/doi/10.1111/apa.12342/full

Study of 3181 children, insufficient evidence to link allergy and cesarean sections.

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