Women with asthma who only use short-acting asthma relievers take longer to become pregnant than other women, according to a new study published in the European Respiratory Journal.
However, the study of more than 5,600 women in Ireland, Australia, New Zealand and the UK also shows that women with asthma who use long-acting asthma preventers conceive as quickly as other women.
While maternal asthma has been consistently associated with significant perinatal morbidities and mortality, impacts on fertility are conflicting, according to the study authors. In light of limited and conflicting evidence, the aim of the study (‘Asthma treatment impacts time to pregnancy: Evidence from the international SCOPE study’) was to examine the impact of asthma and asthma medication use on fecundability and time to pregnancy.
The researchers examined data from the international Screening for Pregnancy Endpoints (SCOPE) study, which recruited more than 5,600 women expecting their first babies in the early stages of pregnancy.
Ten per cent of women in the study said they had asthma and, overall, these women took longer to get pregnant.
When researchers separated this group according to the types of asthma treatments they were using, they found no difference in fertility between women using long-acting asthma treatments and women without asthma.
Women using short-acting reliever medication (beta-agonists) took 20 per cent longer to conceive on average. They were also 30 per cent more likely to have taken more than a year to conceive, which the researchers defined as the threshold for infertility.
This difference remained even after researchers took other factors known to influence fertility, such as age and weight, into account.
The study was led by Dr Luke Grzeskowiak from the University of Adelaide’s Robinson Research Institute, who said that the results provide reassurance for asthmatic women that using inhaled corticosteroids to prevent symptoms does not appear to reduce fertility.
“Five-to-10 per cent of all women around the world have asthma and it is one of the most common chronic medical conditions in women of reproductive age. Several studies have identified a link between asthma and female infertility, but the impact of asthma treatments on fertility has been unclear,” Dr Grzeskowiak said.
“Studying the effect of asthma treatments in women who are pregnant or trying to get pregnant is important, as women often express concerns about exposing their unborn babies to [the] potentially harmful effects of medications.”
While the study showed that women using short-acting asthma relievers take longer to get pregnant, “on the other hand, continued use of long-acting asthma preventers to control asthma seems to protect fertility and reduce the time it takes women with asthma to become pregnant. This could lead to a reduction in the need for fertility treatments”.
“There is plenty of evidence that maternal asthma has a negative impact on the health of pregnant mothers and their babies, and so our general advice is that women should take steps to get their asthma under control before trying to conceive,” he said.
“What we don’t yet know is exactly how asthma or asthma treatments lead to fertility problems. As well as affecting the lungs, asthma could cause inflammation elsewhere in the body, including the uterus. It could also affect the health of eggs in the ovaries.
“Inhaled corticosteroids suppress the immune system, whereas short-acting asthma treatments do not alter immune function. In women who are only using relievers, it’s possible that, while their asthma symptoms may improve, inflammation may still be present in the lungs and other organs in the body.”
The researchers plan further studies involving women with asthma who are undergoing fertility treatments, to see whether improving asthma control could also improve fertility outcomes.
Meanwhile, a separate study presented at the 2017 European Respiratory Society International Congress in Milan found that women with asthma are more likely to have fertility treatment before giving birth than non-asthmatic women.
Among 744 pregnant asthmatic women enrolled in the ‘Management of Asthma During Pregnancy’ programme at the Hvidovre Hospital, Hvidovre, Denmark, and who gave birth between 2007 and 2013, 12 per cent had received fertility treatment compared to 7 per cent of the 2,136 non-asthmatic women in the control group.
Although the study does not prove that asthma played a role in reducing fertility in some women, the researchers said it suggests that improving women’s asthma control might help them to become pregnant more easily.
Prof Charlotte Suppli Ulrik, from the Department of Respiratory Medicine at Hvidovre Hospital, who supervised the study, said: “We don’t have the hard-core evidence but based on what we know, it seems very likely that good asthma control will improve fertility in women with asthma by reducing the time it takes to become pregnant and, therefore, the need for fertility treatment.
“However, when it comes to fertility for women, age is a crucial factor — so the message, particularly for women with asthma, is don’t wait too long, as it might reduce your chances of having children.”
Prof Suppli Ulrik and colleagues are setting up studies to investigate further the association between asthma and fertility, including a study addressing the impact of good asthma control on fertility. “Further studies are needed to confirm our findings,” she said.
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