PURPOSE OF THE STUDY.
There is evidence that the risk for atopic disease is influenced during fetal development and by early life events. This study evaluated the association between preterm birth, very low birth weight (VLBW), and atopy in young adulthood.
Subjects from the Helsinki Study of VLBW Adults were compared to matched controls born at ≥37 weeks' gestation. Of 255 VLBW adults (birth weight: 1120 ± 221 g; weeks of gestation: 29.2 ± 2.2) and 314 controls (birth weight: 3593 ± 471 g; weeks of gestation: 40.1 ± 1.1) invited, 166 (65.1%) and 172 (54.8%), respectively, chose to participate. The mean age at analysis was 22.4 to 22.5 years.
Skin-prick testing was performed to birch, timothy grass, mugwort, cat, dog, and Dermatophagoides pteronyssinus. Total immunoglobulin E (IgE) and serum-specific IgE levels to cat, timothy, and birch were measured. Diagnosis of asthma, allergic rhinitis, and atopic dermatitis were obtained from an unvalidated questionnaire that included physician diagnosis of asthma and allergic rhinitis. The primary outcome of atopy was defined as a positive skin-test result. Other indicators of atopy included elevated total or specific IgE level. Self-reported histories of atopic diseases were secondary outcomes.
VLBW adults were less likely than controls to have at least 1 positive skin-test result (45.5% vs 57.9%; adjusted odds ratio [OR]: 0.48; P = .13). Timothy and mugwort were the only individual allergens associated with a decreased OR in the VLBW group. Adults born at VLBW were also less likely to have any elevated serum-specific IgE level (adjusted OR: 0.48) or an elevated level to cat (adjusted OR: 0.41). Of the adults born at VLBW, those born appropriate for gestational age (AGA) were statistically less likely (P < .05) than those born small for gestational age (SGA) to have a positive skin-test result to dog or D pteronyssinus or to have elevated levels of total serum IgE, serum-specific IgE to any allergen, or serum-specific IgE to birch. Within the VLBW group, each week of earlier gestational age was associated with lower risk of any positive skin-test result or any elevated serum-specific IgE level (OR: 0.82 for each measure). The decreased risk was even more apparent when the SGA adults were excluded from analysis. There was no difference in the frequency of self-reported asthma, allergic rhinitis, or atopic dermatitis between the VLBW adults and controls or between the AGA and SGA VLBW subjects.
Young adults born at VLBW had a greater risk of atopy based on allergen sensitization. There was no difference in the incidence of atopic disease. The results of this study support the hypothesis that the risk for atopy is influenced by early life events.
A weakness of this study is that the incidence of atopic disease itself was based solely on self-report. As the data are reported, being born prematurely and at VLBW places an infant at a lower risk of sensitization to allergen as a young adult. However, the results do not support a decreased risk of allergy (sensitization plus symptoms with exposure).
- Copyright © 2011 by the American Academy of Pediatrics