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Age of entry to day nursery and allergy in later childhood
1Medical Institute of Environmental Hygiene, Heinrich Heine University Düsseldorf, Germany.
Insights
Early childhood daycare attendance may reduce allergy risk. Children in small families attending nursery younger showed less atopy, supporting the infection hypothesis for allergy prevention.
Area of Science:
- Pediatric Allergy and Immunology
- Epidemiology
- Environmental Health
Background:
- Childhood infections are hypothesized to confer protection against later-life allergies.
- Early exposure to infectious agents, such as through daycare, may promote this protective effect.
- This study investigates the relationship between age of nursery entry and the prevalence of atopy.
Purpose of the Study:
- To examine if younger children attending daycare have lower rates of atopy.
- To determine if early exposure to childcare settings influences allergy development.
- To test the hypothesis that early infections protect against allergies.
Main Methods:
- Cross-sectional study of 2471 children aged 5-14 years in eastern Germany.
- Data collected via parental questionnaires on allergies, symptoms, and daycare attendance.
- Atopy assessed through skin-prick tests and serum allergen-specific IgE measurements.
Main Results:
- In small families (≤3 people), later nursery entry (≥12 months) was associated with higher atopy rates (p<0.05).
- Children starting daycare at 24+ months had significantly higher odds of positive skin-prick tests compared to those starting at 6-11 months.
- No significant effect of daycare entry age on atopy was observed in large families (>3 people).
Conclusions:
- Findings support the hypothesis that early infections, potentially acquired in daycare, may protect against the development of allergies.
- The protective effect of early daycare attendance on atopy appears to be modulated by family size.
- Early life exposure to infectious agents may play a crucial role in immune system development and allergy prevention.
Background:
Infections in early childhood may prevent allergies in later life. If this hypothesis is true, early exposure to childcare outside the home would protect against atopy by promotion of cross infections. We investigated whether children who attend a nursery at a young age have a lower rate of atopy and fewer allergies than children who attend from an older age.
Methods:
In a cross-sectional study carried out in 1992-93, we examined 2471 children in three age-groups (5-7, 8-10, and 11-14 years) from the towns of Bitterfeld, Hettstedt, and Zerbst in eastern Germany. The children's parents answered a questionnaire about allergies and symptoms, attendance at day care, and related factors. Sensitisation was assessed by skin-prick tests and measurement of allergen-specific IgE antibodies in serum.
Findings:
In 669 children from small families (up to three people), the prevalence of atopy was higher among children who started to attend day nursery at an older age than in those who started to attend at a younger age (p<0.05). Compared with children who first attended at age 6-11 months, the adjusted odds ratios for a positive skin-prick test were 1.99 (95% CI 1.08-3.66) for children who attended at age 12-23 months and 2.72 (1.37-5.40) for those who attended at age 24 months and older. In 1761 children from large families (more than three people), age of entry to day nursery had no effect on atopy.
Interpretation:
Our findings accord with the hypothesis that early infection may protect against allergies in later life.