SCOPE Study: SABAs associated with reduced fertility in women with asthma

The use of short-acting β-agonists (SABAs) for management of asthma is associated with reduced fertility in women, according to data from the Screening for Pregnancy Endpoints (SCOPE) study. The findings were published in the European Respiratory Journal.

Healthy nulliparous women were recruited for the study from Auckland, New Zealand; Adelaide, Australia; Cork, Ireland; and Manchester and London, United Kingdom. While the primary aim of the SCOPE study was to develop screening tests for prediction of pre-eclampsia, spontaneous preterm birth, and small-for-gestational-age neonates, these data were used to examine the impact of asthma and asthma medication on fertility and time to pregnancy (TTP).

Asthma was self-reported, and women with asthma were divided by symptoms and medication use. They were then classified as having former asthma (diagnosed asthma with no symptoms or medication use in the previous 12 months) or current asthma. Women with current asthma were divided by use of intermittent reliever medications only (ie, SABA), or additional use of reliever medications (ie, inhaled corticosteroids [ICS] with or without long-acting β-agonists [LABA]).

Self-reported TTP was defined as the duration of sex, in months, without contraception prior to the current pregnancy. TTP > 12 months was considered as subfertility. Fecundability odds ratios (FORs) were used to estimate the odds of conceiving in each cycle, given exposure to asthma, conditional on not being pregnant in the previous cycle.

Of the 5,617 women in the study, 19.7% had asthma. Of those women, 11.7% had current asthma, and 8% were former asthmatics. Women with either current or former asthma were younger, had a higher BMI, and were more likely to smoke and report Caucasian ethnicity. They also were more likely to have a lower socioeconomic status.

Results showed that women with current asthma managed with SABAs had adjusted FORs that were 15% lower. No difference was seen in patients with former asthma, or in those with current asthma managed with ICS with or without LABAs.

Subfertility rates were also increased in women who used SABAs. The researchers conducted additional sensitivity analyses that included women who conceived via assisted reproductive technologies, but this did not change any risk estimates.

“We show that asthma is associated with reduced fertility, but the greatest impact is among women with current asthma receiving intermittent reliever treatment with SABAs,” the authors wrote. “The lack of associations with ICS ±LABAs use suggests that preventer medications may play a protective role in improving asthma control and reducing associated systemic inflammation which may drive impaired fertility. This is important as women and health care professionals express concerns regarding the safety of preventer medications such as ICS during pregnancy.”

The authors added that while the exact mechanisms for these findings are unclear, asthma may reduce uterine blood supply or increase infiltration of inflammatory cells in the uterine mucosal layer.

They also acknowledged several limitations of the study. Asthma and medication use was self-reported at 15 weeks’ gestation, and the study design assumed the medication and symptoms reflected the entire period leading up to conception.

A previous study using a self-reported asthma diagnosis was found to have a sensitivity of 68%, so the authors of this study strengthened the identification of asthma to include medication use. However, asthma severity could not be evaluated. In addition, the ability of the data to be generalized to include multiparous women is uncertain.

“These findings support appropriate management of asthma with ICS preventer medications to ensure optimal asthma control,” the authors concluded. “Women with asthma planning a pregnancy should be encouraged to continue taking their preventer medications.”

To read more about this study, click here.