Lower body mass index (BMI) during maternal pregnancy and antibiotic treatment during delivery have been shown to increase the risk of allergic sensitization in children, according to a recent study.
The prevalence of allergic diseases has been increasing since the beginning of the 20th century, with the determinants that favor the allergic phenotype being small family size, sex, smoking, duration of breastfeeding, genetic factors, and living in less likely environments. rural. The urbanization of society, changes in diet and newer hygienic conditions have all contributed to changes in human lifestyle and, consequently, to allergic sensitivity, explained study author Reetta Puisto MD, of the Department of Pediatrics and Faculty of Medicine at the University of Turku in Finland, and colleagues.
Today, antibiotics are also frequently used from a young age, with 40% of all newborns exposed to antibiotics during childbirth. This increase in use, the urbanization of society, and modern trends in lifestyle and environmental exposures may have contributed to the recent increases in allergic sensitization. The combination of risk factors known to predispose children to allergic diseases, along with the prevalence of antibiotics and lifestyle trends in the modern world, were the factors that motivated the study by Puisto and colleagues.
“Today’s mothers are more obese, give birth at an older age and more often by cesarean section; this global trend appears to be continuing,” they wrote. “In modern medicine, antibiotics are widely used from the first years of life without fully understanding the long-term effects.”
Research and methods
The investigators used a nested case-control trial design, based on 3 ongoing probiotic intervention trials aimed at reducing the risk of atopic disease. A total of 656 families contributed to the original studies, of which 433 children were eligible for the study based on inclusion criteria, such as being born to mothers with asthma, atopic dermatitis, hay fever, food allergy, or allergic sensitization. This was done in order to target the study to children with genetic predispositions.
The primary clinical endpoints of the study were allergic manifestations within the study population in the first 2 years of life. Information on known risk factors for allergic diseases was obtained from prospectively collected study records for the investigation, with the factors being:
- Child sex
- have older siblings
- Maternal smoking during pregnancy
- duration of lactation
- Maternal BMI prior to pregnancy
- Delivery mode
- Maternal intrapartum antibiotic treatment
- Infant antibiotic treatment during the first 6 months of life
- Probiotic intervention during pregnancy and after delivery
- Having ≥1 furry pet during pregnancy or early childhood
During scheduled follow-up visits, study physicians clinically diagnosed atopic dermatitis during their scheduled follow-up visits. They used modified criteria that included pruritus, typical morphology and distribution, and relapsing chronic course with ≥2 eczema episodes lasting at least 1 month each, or persistent chronic eczema without periods of remission.
Inhaled corticosteroids (ICS) were also used in the study as an objective proxy for obstructive respiratory symptoms due to allergic sensitization. ICS purchasing information was compiled from the Finnish National Prescription Register.
Skin prick testing (SPT) was also used to assess allergic sensitization, and the tests were performed by trained study nurses at ages 6 months, 12 months, and 24 months. Cow’s milk and egg white, the most relevant food allergen sources for children ≤2 years, were observed in the SPT panels.
A total of 231 children developed atopic dermatitis, were prescribed ICS, received positive SPT results within the first 2 years of life, or had physician-prescribed food allergies, and were therefore identified as cases. Another 202 children were identified as healthy controls.
Lower maternal BMI prior to pregnancy (adjusted odds ratio [aOR], 0.15; 95% CI, 0.037 – 0.54) and intrapartum maternal antibiotic treatment (aOR, 2.21; 95% CI, 1.20 – 4.10) were associated with a significantly decreased and increased risk of dermatitis atopic, respectively. Obstructive respiratory symptoms (aOR, 3.87; 95% CI, 1.07 – 14.06) were also associated with significantly increased risks.
The researchers also found similar associations between risk of allergic sensitization and lower maternal BMI before pregnancy (aOR, 0.18; 95% CI, 0.43 to 0.79) and intrapartum antibiotic treatment (aOR, 2 .13, 95% CI, 1.07 to 4.22).
The researchers concluded that their findings reinforce the idea that both pregnancy and early childhood represent critical periods in a child’s life for the development of the immune phenotype.
“We are just beginning to understand the potentially detrimental consequences of heavy antibiotic use and the treacherous rise in maternal obesity for the long-term health of children,” they wrote. “Women of childbearing potential should be advised to aim for a normal weight, and if antibiotic treatment during labor or in early childhood is considered, the potentially increased risk of allergies should be taken into account.”
The study, “Early Life Exposures and Allergic Disease Development in Infants at Familial Risks: Results of Ongoing Probiotic Intervention Trials,” was published online at Pediatric Act.
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