IVF babies twice as likely to get asthma, say scientists
In the most extreme cases, the risk is increased almost five times, according to new study findings.
Children conceived with artificial help are also more likely to wheeze or take anti-asthmatic medicines by the age of five.
Scientists discovered the link after analysing data on 18,818 children from across the UK born between 2000 and 2002.
But they point out that the association may not be causal, and the chances of a child conceived after IVF treatment becoming asthmatic are still slim.
Researchers conducting the UK Millennium Cohort Study compared children in different groups with those born after natural planned pregnancies.
Children born to sub-fertile parents were 39pc more likely to have asthma symptoms by the age of five and 27pc more likely to wheeze.
Closer study showed that the association was mainly driven by children conceived via some form of assisted reproduction technology (ART). This includes IVF ( in-vitro fertilisation) and ICSI (intra-cytoplasmic sperm injection), which involves injecting sperm directly into eggs.
However, only 104 children fell into this category, leading the scientists to urge caution when interpreting the results.
The findings are published today in the journal Human Reproduction.
Lead researcher Dr Claire Carson, from Oxford University, said: "Childhood asthma is a common condition in the UK where the prevalence of the condition is higher than other European countries and, to our knowledge, this is the first UK study of asthma after IVF conceptions.
"Our analysis suggests that it is the ART group in particular who are at higher risk."
There could be a number of possible explanations for the link between infertility, IVF and asthma, say the researchers. The scientists took account of mothers' asthma and smoking history, body mass index (BMI), socio-economic status, the presence of furry household pets and other factors that could have swayed the findings.
But they acknowledge there could be other confounding influences.