Perinatal risk factors for asthma in Finnish adolescent twins

Abstract

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 eVect 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 diVers 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. (Thorax 2000;55:25-31)

Genetic and Environmental Factors in Health-related Behaviors: Studies on Finnish Twins and Twin Families

“…As she has summarized in her dissertation, the genetic contribution to variance in liability to both asthma and hay fever was found to be high Räsänen et al, 1998). In addition to corresponding parental disease, a high ponderal index at birth and maternal smoking also proved to be risk factors for asthma (Räsänen et al, 2000), while male gender, small sibship and gestational maturity proved to be independent risk factors for hay fever (Räsänen et al, 1997). The relative contribution of genes vs. environment in disease liability and the effect of perinatal risk factors for asthma and hay fever varied according to parental disease status.…”

Perinatal Risk Factors for Hay Fever — A Study Among 2550 Finnish Twin Families

“…Because the occurrence of hay fever among adolescents with farming fathers was distinct from that of children with fathers in the other occupational groups, the other occupational groups' data were pooled. The variables and methods of the present study have been described in more detail previously (Räsänen et al, 2000).…”

A Note on Twin–Singleton Differences in Asthma

“…Räsänen and colleagues studied 3065 Finnish twin pairs and found that the heavier twin at birth (as indicated by ponderal index) had an increased risk of asthma at age 16 compared with his or her twin brother or sister (Räsänen at al., 2000). The relationship was stronger in fraternal than in identical twins consistent with common genetic influences on asthma and birthweight.…”