Does parental subfertility and unmeasured confounding have an impact on the association between assisted reproductive technologies (ART)  and childhood asthma? New research explores this question.

The role of time to conception in childhood asthma pathogenesis is not known. Interestingly, asthmatic women have greater difficulty conceiving than non-asthmatic women, leading to a need for ART, which, in turn, may be linked to an increased risk of asthma. Children born during 2000 and 2002 to subfertile parents were significantly more likely to develop asthma and be taking medications at age 5, according to a sub-analysis of the observational, multidisciplinary U.K. Millennium Cohort Study of 18,818 children recruited at 9 months of age and prospectively followed at age 5 and 7.

For the current study, Maria Christine Magnus, PhD, of the Norwegian Institute of Public Health in Oslo, and colleagues said that based on these findings, one hypothesis is that maternal asthma is associated with childhood asthma and that subfertility and corresponding treatment may be hitherto unknown risk factors for the pediatric disease.

The researchers analyzed data from the national Norwegian health registries on 474,402 children born during 1998 and 2009 and on the Norwegian Mother and Child Cohort Study (MoBa) involving 75,797 children. The team linked data from a national birth registry and a national prescription database to identify children who had been born using ART and who also used asthma medication.