How Your Fertility Affects Your Children’s Asthma Risk
A new study published in Thorax suggests that a couple’s fertility may impact the likelihood that their children develop asthma. Previous research had shown that children who are conceived with the help of fertility treatments, known as assisted reproductive technologies (ARTs), may be at heightened risk for asthma. However, existing data have made it hard to determine if fertility treatments themselves lead to increased asthma risk, if the culprit could instead be whatever factor led to the couple’s reduced fertility, or if some other factor or combination of factors was to blame.
To help clarify the relationship between fertility and asthma risk in offspring, a research group leveraged data from national Norwegian health registries that included information on nearly 475,000 children who were born between 1998 and 2009. Included in these data were information on the use of fertility treatments, the time to conception, details of previous miscarriages, and maternal factors such as age, asthma status, weight, and smoking habits.
The researchers’ results corroborated previous findings that children conceived with the aid of ARTs are at a higher risk for developing asthma. Indeed, the researchers found that those conceived through fertility treatments were 42 percent more likely to develop childhood asthma – defined as the use of asthma medications during the previous year when children were seven – than those conceived in the absence of fertility treatments.
However, asthma risk also correlated with other factors indicative of fertility. For instance, children of those who took more than a year to conceive were more likely to develop asthma, as were those whose mothers had previously suffered first trimester miscarriages. The risk amongst children of mothers who had miscarried increased with the number of miscarriages. While the risk for asthma was seven percent higher in children whose mothers had experienced one miscarriage than in those who had experienced no miscarriages, the risk increased 24 percent for those whose mothers had had three or more miscarriages.
The increased risk amongst children of mothers with three or more miscarriages was comparable to the increased risk observed in those whose parents took over a year to conceive. The increased risk in the latter group was 22 percent. While these data point to a relationship between fertility and asthma in offspring, the increased risk of asthma observed in children who were conceived with the help of fertility treatments was much higher. These children experienced a heightened asthma risk of 42 percent
Parental fertility appears to play a role in children’s asthma risk, but something about fertility treatments or those who undergo those treatments may contribute more significantly to this risk than does low fertility itself. According to experts, ART procedures—including the modification of the hormonal environment—may affect fetal development and may account for some of the increased risk for asthma that is observed in children conceived through these methods. Future research will help to clarify the specific link between parental fertility and children’s asthma risk and hopefully provide insights into how we can intervene to reduce asthma risk in these children.