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Two studies show links between asthma and fertility treatment, and between e-cigarette vaping in mothers and asthma in offspring

Two studies show links between asthma and fertility treatment, and between e-cigarette vaping in mothers and asthma in offspring

Asthma linked to increase in fertility treatment

Milan, Italy: Women with asthma are more likely to have fertility treatment before giving birth than non-asthmatic women, according to new research presented today (Tuesday) at the European Respiratory Society International Congress.

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% had received fertility treatment compared to 7% 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 say it suggests that improving women’s asthma control might help them to become pregnant more easily.

Professor 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.

Pregnant women were eligible for the study if they had a diagnosis of asthma and had their first visit to the respiratory clinic within the first 18 weeks of pregnancy. Each asthmatic woman was matched with three consecutive non-asthmatic women who gave birth at the hospital; these women made up the control group. The researchers looked at whether the births in both groups were due to spontaneous conception, or whether the women had had assisted reproductive technology (e.g. in vitro fertilisation – IVF) or intrauterine insemination, regardless of the cause of the infertility.

Women in the asthmatic group and the control group were similar with regard to age, with an average age of 31.3 years in the asthmatic group (ranging from 17 to 44 years old) and 30.9 years in the control group (ranging from 17 to 45 years old). The researchers adjusted their results to take account of factors that could affect the results such as age, body mass index, whether or not the women smoked, had had previous children, were single or in a same-sex partnership. However, Prof Suppli Ulrik said they could not rule out that the two groups might differ with regard to income, life style and socio-economic factors.

Offspring of female mice exposed to e-cigarette vaping have increased risk of allergic asthma

In a second presentation to be given tomorrow (Wednesday) researchers found that maternal e-cigarette vaping was linked to an increased risk of allergic asthma in offspring. The study was carried out in mice, but Dr Pawan Sharma, Chancellors Fellow and Research Leader in the Airways Disease Group at the University of Technology Sydney, Australia, will tell the congress: “These findings highlight that e-cigarette use during pregnancy should not be considered safe.”

Allergic asthma is caused by a reaction to allergens such as pollen, dust mites and pets. Dr Sharma and colleagues exposed female mice, before mating, to either e-cigarette vapour, with or without nicotine, or to normal room air. The mice continued to vape during pregnancy, birth and while they were feeding their young. The offspring were then exposed to an allergen made from ovalbumin (the major proteins found in eggs) until they developed asthma.

The researchers also exposed human cells to varying concentrations of e-cigarette liquid in the laboratory and measured the functioning of mitochondria (battery-like molecules that power key processes, such as respiration, in cells).

“Our study found that maternal vaping increased the risk and severity of allergic asthma in offspring. We also found that the detrimental effects of vaping were partially mediated through impairment of mitochondrial function, which affects cellular respiration, and were independent of nicotine. This means that vaping, even without nicotine present, has a demonstrated negative impact on cell function,” says Dr Sharma.

“It is now known that maternal tobacco smoking is detrimental to lung health and increases the risk and severity of allergic airways disease in children. E-cigarette vaping is comparatively new, but emerging research suggests that its use is growing rapidly worldwide. There is a perception that vaping is a safer alternative to cigarette smoking and it is increasingly being viewed as a tool to help quit smoking during pregnancy. However, studies of the safety of maternal vaping for offspring, especially the subsequent development of allergic airways disease, are lacking. Our study demonstrates that maternal vaping is associated with impaired lung function and an increased risk of asthma in offspring. Action is needed to remove the general public’s false impression that all e-cigarettes are safe and effective smoking cessation aids.”

The researchers are carrying out further studies to understand the mechanism by which e-cigarette vaping enhances allergic inflammation and worsens asthma.

Dr Sharma concludes: “Because e-cigarettes do not require combustion unlike traditional tobacco cigarettes, vaping produces reduced levels of toxic compounds. However, it is now becoming increasingly clear that vaping can still expose humans to numerous compounds that are toxic in nature and have undesirable effects. Moreover, the availability of different e-cigarette flavours and the use of nicotine on top has the potential to create a dangerously addictive concoction leading to unwanted health outcomes.”

Notes to editors

[1] Abstract no: PA3587, “Fertility treatment in women with asthma – a case-control study of 2,880 women with live births”, by Zarqa Ali et al; Thematic poster session, 12.50-14.40 hrs CEST, Tuesday 12 September, TP-02 (Hall 4).

[2] Abstract no: PA4694, “Maternal eCigarette vaping enhances Th2 driven asthma in the offspring”; Poster discussion session, 08.30-10.30 hrs CEST, Wednesday 13 September, Amber 1+2 (south).

Research for abstract PA3587 was funded by the Danish Lung Foundation.

Research for abstract PA4694 was funded by the University of Technology Sydney and the National Health & Medical Research Council, Australia.

In the European Union (EU) ever use of e-cigarettes increased from 7.2% in 2012 to 11.6% in 2014 according to a paper first published in 2016: “Two-year trends and predictors of e-cigarette use in 27 European Union member states”, Filippidis FT, Laverty AA, Gerovasili V, et al. Tob Control 2017;26:98–104.