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Perinatal risk factors for asthma in Finnish adolescent twins
M Räsänen1, J Kaprio, T Laitinen
1Helsinki University Central Hospital, Department of Medicine, Division of Pulmonary Medicine, FIN-00029 HUCH, Finland.
Insights
Infant ponderal index, a measure of weight relative to length, is linked to increased asthma risk in adolescents. This finding holds true even when considering family history and social factors, highlighting intrauterine influences on childhood asthma development.
Area of Science:
- Pediatric Allergy and Immunology
- Twin Studies Research
- Epidemiology of Respiratory Diseases
Background:
- Intrauterine conditions, alongside genetics and early environment, may influence childhood asthma risk.
- Perinatal factors like low birth weight and maternal smoking have been previously associated with asthma.
- Twin studies offer a unique model to disentangle genetic and environmental contributions to asthma development.
Purpose of the Study:
- To investigate the impact of perinatal factors on asthma risk in adolescents.
- To examine the interplay between perinatal, familial, and social risk factors for adolescent asthma.
- To leverage a nationwide twin cohort to assess environmental and genetic influences on asthma.
Main Methods:
- A nationwide population-based study of Finnish adolescent twins (born 1975-1979) and their parents.
- Data collected via questionnaires on lifetime prevalence of doctor-diagnosed asthma.
- Statistical analysis included multiple logistic regression and discordant twin pair analysis.
Main Results:
- Asthma risk positively correlated with ponderal index (PI) and inversely with maternal age.
- Adolescents in the highest PI quartile had an 82% increased odds of asthma (OR 1.82).
- Ponderal index, maternal smoking, parental asthma, and sibship size were independent predictors of asthma when combined with other factors.
Conclusions:
- Increased ponderal index during infancy is a significant risk factor for adolescent asthma.
- The association between ponderal index and asthma risk persists after adjusting for familial and social factors.
- Intrauterine growth, as indicated by PI, plays a role in asthma development beyond childhood.
Background:
Previous studies have suggested that, in addition to genetic liability and environment in early childhood, intrauterine life also influences the risk for asthma beyond childhood. Low birth weight, prematurity, young maternal age, and maternal smoking have all shown an association with asthma. The effect of perinatal factors on the risk for asthma in relation to familial and social risk factors was studied in a nationwide population-based sample of adolescent twins. In addition to a distribution of birth characteristics among twins which differs from that of singletons, data on twins enable a distinction to be made between genetic and environmental sources of variation.
Methods:
Questionnaires were sent to five consecutive birth cohorts of Finnish 16 year old twins born in 1975-9 and to their parents (3065 families). The outcome measure was life time prevalence of doctor-diagnosed asthma in these adolescents. The association between asthma and potential risk factors was assessed by multiple logistic regression and discordant twin pair analysis.
Results:
Risk for asthma increased with increasing ponderal index (p for trend <0.01) and decreasing maternal age (p for trend <0.05). Among the 25% of twins with the highest ponderal index, the odds ratio for asthma was 1.82 (95% confidence interval 1.18 to 2.79) compared with those in the lowest 25%. Neither birth weight, gestational age, nor Apgar score was associated with asthma. When perinatal risk factors were combined with familial and social risk factors, ponderal index, maternal smoking, parental asthma, and sibship size were all significant independent determinants of asthma in these adolescents.
Conclusions:
The risk for asthma in adolescent twins increases with increasing ponderal index when adjusted for familial and social factors.