Asthma inhalers may be linked to birth defects, the Daily Mail has today reported. The newspaper said that new research has linked steroid asthma pumps "to a slightly increased risk of hormonal and metabolic disorders in babies"
The research was from a Danish study that looked at whether the risk of developing a variety of early childhood diseases was linked to their pregnant mother’s use of glucocorticoid steroid inhalers - a standard preventative treatment for asthma.
The national study looked at over 65,000 Danish women who gave birth between 1996 and 2002, 6.3% of whom had asthma, and followed the children to an average of six years. The researchers looked at a wide range of disease types but found the use of inhalers was only linked to an increased risk of developing an endocrine (hormonal) or metabolic disorder during early childhood.
Further research into the long-term effects of inhaled corticosteroids is warranted, and additional research to confirm the finding of this research is needed. In the meantime, recommendations on the use of steroid inhalers are unlikely to change. Pregnant women prescribed inhaled steroids should continue to take these medications as advised as the benefits of using this medication are likely to outweigh the risks, especially in women who have severe asthma.
The study was carried out by researchers from the University of Basel, Ruhr-University Bochum and other medical and research institutions throughout Europe and the US. The research was funded by the Danish National Research Foundation, the Swiss National Science Foundation, the German National Academic Foundation and Research Foundation of the University of Basel.
The study was published in the peer-reviewed American Journal of Respiratory and Critical Care Medicine.
This study was not widely reported in the media; however, the Daily Mail did focus on it in a story about prescription drugs and risk of birth defects. The story mentioned a range of different types of prescription drugs that could be linked to birth defects, although it mainly discussed a possible link between asthma inhalers and birth defects. While the story did mention that the research found only a slightly increased risk in one category of diseases, it did not report that this study found no significant increased risk for most diseases.
Throughout its article the Mail referred to a ‘major inquiry’ and an ‘investigation’ into the use of a variety of medications during pregnancy. The research in question is the EUROmediCAT study, a large ongoing project to look at the use of medication during pregnancy. The way the project was described might lead readers to assume it is some sort of emergency investigation or was set up as the result of a specific health scare. However, it is an ongoing scientific study and does not suggest any kind of health scare or emergency at present.
This Behind the Headlines article focuses on the study looking at inhalers and potential birth defects, rather than the EUROmediCAT study.
This was a national cohort study that aimed to assess the association of women using glucocorticoid inhalers for asthma during pregnancy and their child’s risk of developing several types of disease during the first several years of life.
Previous research into the safety of inhaled glucocorticoids has suggested that they are safe to use during pregnancy, and are not associated with increased risk of birth defects. This research has provided the basis for many policies recommending the continued use of inhalers for the treatment of asthma during pregnancy. The researchers say, however, that these studies only examined the short-term risks, and that research should assess the children for longer to determine if there are any longer-term associations with a wider variety of diseases.
A prospective cohort study is an appropriate design for assessing associations such as long-term outcomes of medicine use, as it collects information on a range of factors before any outcomes develop, and then goes on to see how they might account for any relationship that develops.
This study analysed data from the Danish National Birth Cohort, which included births between 1996 and 2003. Women were invited to participate during their first antenatal visit, at around 6 to 12 weeks of pregnancy. Approximately 60% of the invited women decided to participate. Interviews during and after pregnancy were conducted, and researchers assessed the development of disease during early childhood by examining medical registries.
For this substudy looking specifically at the use of certain asthma medications, the researchers extracted data from the Danish National Birth Cohort on women with asthma who gave birth to a single baby (women carry twins or other multiples were not included in the analysis).
Women were considered as having asthma if the condition occurred at any time during the current pregnancy. Researchers recorded information on the type of asthma treatment at several times during the study - at weeks 12 and 30 of pregnancy and at six months after birth.
Researchers also collected information on the child relating to diagnoses in a number of disease types based on the International Classification of Diseases, version 10. They used a statistical technique called regression analysis to assess the association between use of inhaled corticosteroids and the development of these disease types during early childhood:
During these analyses the researchers included several measures that have been shown to impact on early childhood health, including socioeconomic status, mother’s occupation, the number of previous pregnancies, child sex, and the use of any non-steroid inhalers during the pregnancy. This allowed them to assess the influence any of these factors might have on the relationship between maternal inhaler use and the risk of early childhood diseases.
There were 65,085 mother-child pairs enrolled in the original Danish National Birth Cohort. Of these, 4,083 (6.3%) had asthma during pregnancy and were included in the current analysis. Of women with asthma, 1,231 (30%) used steroid-inhalers during pregnancy, the most common of which was budesonide. The median (average) child age at the end of the study was 6.1 years (range 3.6 to 8.9 years).
In all, 2,443 children developed a disease during early childhood. When the researchers compared the risk of developing diseases between the children of women who used inhaled corticosteroids compared to the children of women who did not, they found there was no significant difference in risk for the following categories:
A total of 93 children (2.28% of the asthma cohort) developed an endocrine or metabolic disorder during early childhood. The endocrine system is made up of various glands that release hormones into the blood. The metabolism is the system the body uses to turn food into energy.
The researchers calculated that children of women who used inhaled glucocorticoids during pregnancy had 62% increased risk of developing an endocrine or metabolic disorder, compared to children of women who did not use the inhalers (hazard ratio 1.62, 95% confidence interval 1.03 to 2.54, p=0.036).
The researchers concluded that use of glucocorticoids during pregnancy was not associated with an increased risk of the child developing most diseases during early childhood compared to the children of mothers with asthma who did not use the treatment. The only disease category in which use of inhalers was associated with an increased risk was endocrine and metabolic disorders.
This large cohort study suggests that the use of inhaled glucocorticoids for the treatment of asthma during pregnancy does not increase the risk of developing most types of disease during early childhood. As the researchers say, this data is ‘mostly reassuring’ and supports the use of these inhalers during pregnancy.
The study did find an increased risk of developing endocrine or metabolic disorders in children of mothers with asthma who used steroid inhalers during pregnancy. However, it is important to remember that the increased risk is relative to children of women with asthma who did not use inhaled steroids, and that only 93 children developed an endocrine or metabolic disorder of the 4,083 whose mothers who had asthma during pregnancy.
The study does not give absolute numbers of children with these conditions whose mothers did and did not use steroid inhalers, but the absolute risk for both groups is likely to be quite low.
The researchers say that their results regarding this increased relative risk for endocrine and metabolic diseases should be investigated further. They point to several limitations of their study, including the fact that they relied upon a clinical diagnosis of a disorder and did not consider other potentially more sensitive measures. In addition, the researchers did not have information on diagnoses made by the childrens’ GPs, and therefore may have missed out on a diagnosis of less severe disease.
They also say that some disease categories had very small number of diagnoses (such as cancers and blood and immune system diseases), which may have resulted in an imprecise estimation of the hazard ratios.
An editorial accompanying this study suggested that the results be interpreted with caution, given some of the study limitations, such as the fact that the analysis did not control for asthma severity or patients’ use of other treatments alongside their inhalers. They say that it is unclear whether the findings are the result of women using inhaled steroids for the management of more severe asthma.
Pregnant women who have been prescribed inhaled steroids for asthma should continue to take these medications as advised, as well-controlled asthma is important for the health of both the mother and the baby.
Women who have any concerns about the medical management of their asthma during their pregnancy should speak with their doctor.