Asthma and the menopause: a systematic review and meta-analysis

Effects of menopause and fat mass in asthmatic inflammation

INTRODUCTION

Female hormones and obesity have an impact on women with asthma. We aimed to describe how these components affect asthma inflammatory processes.

METHODS

Sex hormones [FSH, LH, estradiol (E2), estrone (E1), testosterone and Δ4 androstenedione (A4)] and serum IL1β, IL13, IL17a, IL-5, IL6, TNF-a were measured from 11 to18 pre- and postmenopausal women with asthma.

RESULTS

Premenopausal normal weight women revealed higher levels of IL5 and IL17a than obese women on both days of the menstrual cycle (IL5: D1: 6.4 vs 1.4 pg/ml, p = .036 and D14: 3 vs 1.4 pg/ml, p = .045 and IL17a: D1: 13.7 pg/ml vs 10.6 pg/ml and D14: 12.4 pg/ml vs 10.6 pg/ml, p = .009, respectively). In premenopausal women on D1, Δ4 Androstenedione was positively correlated with IL1β (p = .016, r = 0.733), whereas on D14, Estradiol with IL1β (p = .009, r = -.768) and TNF-a with Testosterone (p = .004, r = -0.816), and Δ4 Androstenedione (p = .002, r = -0.841) negatively. In postmenopausal women, TNF-a was negatively associated with FSH (p = .004, r = -0.638), but positively with Testosterone (p = .025, r = 0.526) and IL10 also positively with Estradiol (p = .007, r = 0.610).

CONCLUSION

Obesity shows a protective role in asthma through the suppression of IL5 and IL17. Estrogens seem to inhibit Th1 and Th2 inflammation, while androgens have a dual role with negative and positive correlations with neutrophilic biomarkers.

Interleukin-4 (C590T) Gene Polymorphism in Association with Asthma Severity

Background

A significant link between T allele of the IL-4 (C590T) gene and developing asthma in some populations was reported. However, no study discussed the link between IL-4 (C590T) gene polymorphism and asthma severity groups (mild and severe). This study investigated the link between IL-4 gene variation and asthma severity.

Methods

The study included 215 asthmatic patients, of which 102 had mild asthma, and 126 participants were healthy controls. A previously published polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify various IL-4 (C590T) gene polymorphism genotypes.

Results

The T allele frequency was higher in mild asthma (p=0.002) but not in severe asthma (p=0.12) compared to controls. In mild asthma, the CT genotype and (CT+TT versus CC) increased the likelihood of asthma threefold (p<0.001, 0.001). However, no significant association with severe asthma was found in either genetic model. Stratification analysis showed that the C allele and CC genotype increased the risk of severe asthma (p=0.01). The recessive genetic model indicated a decrease in the risk of severe asthma (OR=0.5, p=0.01) in the non-adjusted regression analysis. Adjusting for age, sex, and other risk factors revealed that the IL-4 gene polymorphism did not influence the risk of severe asthma (OR=0.92, p=0.80); however, being an elderly female with a history of childhood-onset disease and associated nasal polyp (NP) increased the likelihood of severe asthma, OR=1.08, 2.01, 2.36, 8.42; p<0.001, 0.05, 0.05, <0.001, respectively.

Conclusion

The T allele and CT genotype in the co-dominant genetic model and the (CT+TT) genotype in the recessive model were found to have a higher likelihood of developing mild asthma but not severe asthma; severe asthma was found to be higher in elderly females with a history of childhood-onset disease and associated nasal polyps.

Sex Plays a Multifaceted Role in Asthma Pathogenesis

Sex is considered an important risk factor for asthma onset and exacerbation. The prevalence of asthma is higher in boys than in girls during childhood, which shows a reverse trend after puberty—it becomes higher in adult females than in adult males. In addition, asthma severity, characterized by the rate of hospitalization and relapse after discharge from the emergency department, is higher in female patients. Basic research indicates that female sex hormones enhance type 2 adaptive immune responses, and male sex hormones negatively regulate type 2 innate immune responses. However, whether hormone replacement therapy in postmenopausal women increases the risk of current asthma and asthma onset remains controversial in clinical settings. Recently, sex has also been shown to influence the pathophysiology of asthma in its relationship with genetic or other environmental factors, which modulate asthmatic immune responses in the airway mucosa. In this narrative review, we highlight the role of sex in the continuity of the asthmatic immune response from sensing allergens to Th2 cell activation based on our own data. In addition, we elucidate the interactive role of sex with genetic or environmental factors in asthma exacerbation in women.

Sex, Cells, and Asthma

There are marked sex differences in asthma prevalence and severity. Sex hormones play a central role in these sex biases and directly interact with multiple key cells involved in the pathogenesis of asthma. Here we review the known effects of estrogen, progesterone, and testosterone on airway epithelial cells, airway smooth muscle cells, the mononuclear phagocyte system, innate lymphoid cells, eosinophils, mast cells, T cells, and B cells, all in the context of asthma. Furthermore, we explore unresolved clinical questions, such as the role of sex hormones in the link between asthma and obesity.

Preventive oral kefir supplementation protects mice from ovariectomy-induced exacerbated allergic airway inflammation

Asthma is an inflammatory lung disease that affects more women than men in adulthood. Clinical evidence shows that hormonal fluctuation during the menstrual cycle and menopause are related to increased asthma severity in women. Considering that life expectancy has increased and that most women now undergo menopause, strategies to prevent the worsening of asthma symptoms are particularly important. A recent study from our group showed that re-exposure of ovariectomised allergic mice to antigen (ovalbumin) leads to an exacerbation of lung inflammation that is similar to clinical conditions. However, little is known about the role of probiotics in the prevention of asthma exacerbations during the menstrual cycle or menopause. Thus, our objective was to evaluate the effects of supplementation with kefir, a popular fermented dairy beverage, as a preventive strategy for modulating allergic disease. The results show that the preventive kefir administration decreases the influx of inflammatory cells in the airways and exacerbates the production of mucus and the interleukin 13 cytokine. Additionally, kefir changes macrophage polarisation by decreasing the number of M2 macrophages, as shown by RT-PCR assay. Thus, kefir is a functional food that potentially prevents allergic airway inflammation exacerbations in ovariectomised mice.

Sex and gender: modifiers of health, disease, and medicine

Clinicians can encounter sex and gender disparities in diagnostic and therapeutic responses. These disparities are noted in epidemiology, pathophysiology, clinical manifestations, disease progression, and response to treatment. This Review discusses the fundamental influences of sex and gender as modifiers of the major causes of death and morbidity. We articulate how the genetic, epigenetic, and hormonal influences of biological sex influence physiology and disease, and how the social constructs of gender affect the behaviour of the community, clinicians, and patients in the health-care system and interact with pathobiology. We aim to guide clinicians and researchers to consider sex and gender in their approach to diagnosis, prevention, and treatment of diseases as a necessary and fundamental step towards precision medicine, which will benefit men's and women's health.

Associations between prenatal exposure to DDT and DDE and allergy symptoms and diagnoses in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), South Africa

Dichlorodiphenyl trichloroethane (DDT) is an organochlorine insecticide that is banned internationally except for use as part of Indoor Residual Spraying (IRS) programs to control malaria. Although animal studies show that DDT and its breakdown product dichlorodiphenyl dichloroethylene (DDE) affect the immune system and may cause allergies, no studies have examined this question in populations where IRS is conducted. The aim of our study was to investigate whether prenatal exposure to DDT and DDE is associated with allergy symptoms and diagnose among South African children living in an area where IRS is conducted. To accomplish this aim, we used data from the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE), an ongoing birth cohort study of 752 children born between 2012 and 2013 in the rural Vhembe district of Limpopo, South Africa. We measured maternal peripartum serum concentrations of DDT and DDE, and administered a questionnaire to the caregivers of 658 children aged 3.5 years to collect information on allergy symptoms and diagnoses as well as potential confounders using validated instruments. Using multiple logistic regression models, we found positive associations between DDT and DDE serum concentrations and most of the allergy symptoms and diagnoses. Maternal DDT (Odds Ratio [OR] = 1.5 per 10-fold increase, 95% Confidence interval, CI = 1.0, 2.3) and DDE (OR = 1.4, 95% CI = 0.8, 2.4) serum concentrations were most strongly associated with caregiver report of wheezing or whistling in the chest. Concentrations of DDT and/or DDE were also associated with increased odds of children's chests sounding wheezy during or after exercise, itchy rashes coming and going for at least six months, diagnosis of food allergy, and diagnosis of dust or dust mites allergy but confidence intervals crossed the null. Results suggest that prenatal exposure to DDT, and possibly DDE, is associated with elevated odds of wheezing among children from an IRS area.

Current status and perspectives regarding the association between allergic disorders and cancer

While activation of immune system may lead to a lower risk of some diseases, it has been shown that a history of atopic allergic disorders such as asthma, hay fever, eczema, and food allergies could be related to several types of cancer. However, the evidence is not entirely conclusive. Two proposals suggest a possible mechanism for the association between allergic disorders and cancers: immune surveillance and the antigenic stimulation. The association of allergy and cancer may vary by cancer site and the type of exposure. The aim of current review was to summarize the current knowledge of the association between allergic diseases and the risk of cancers with particular emphasis on case-controls and cohort studies to estimate the cancer risk associated with allergy.

[Woman's asthma throughout life: Towards a personalized management?]

In a woman's life, asthma can affect her in a variety of ways, with the onset of premenstrual asthma currently under-diagnosed. It is estimated that about 20% of women with asthma have premenstrual asthma, which is more common in patients with severe asthma. Women with asthma are at high risk of exacerbations and of severe asthma. Asthma is the most common chronic disease during pregnancy with potential maternal and foetal complications. Asthma medications are safe for the foetus and it is essential to continue pre-existing treatment and adapt it to the progress of asthma during the pregnancy. Sex steroids modulate the structure and function of bronchial and immune cells. Understanding their role in asthma pathogenesis is complicated by the ambivalent effects of bronchodilating and pro-inflammatory oestrogens as well as the diversity of response to their association with progesterone. Menopausal asthma is a clinical entity and is part of one of the phenotypes of severe non-allergic and low steroid-sensitive asthma. Targeted assessment of the domestic and professional environment allows optimization of asthma management.

Novel Insights on Sex-Related Differences in Asthma

PURPOSE OF REVIEW

Asthma, a common respiratory disease that affects about 10% of the US population, represents a significant public health issue. In the last decade, cumulative evidence has demonstrated sex disparities in asthma, including significant differences in epidemiology, clinical presentation, response to therapies, and health outcomes. Understanding sex-related differences in asthma enables clinicians to provide personalized asthma care and improve asthma outcome.

RECENT FINDINGS

Recent studies on sex-related differences in asthma inform us on mechanism underlying asthma pathogenesis across all age groups. Sex hormones directly modulate immune pathways crucial in asthma pathogenesis and affect individual's response to environmental triggers and medications, such as leukokotriene inhibitors. Not surprisingly, the use of external sex hormone supplementations appears to modulate asthma risk. Identification of sex-specific asthma risk loci through genome-wide association studies also provides supporting evidence on sex-related differences in asthma. There is an interaction between sex and obesity, an interaction that could place females at higher risk for systemic inflammation and, consequently, asthma. In this article, we review epidemiological and clinical studies on sex-related differences in asthma, with a special focus on the role of sex hormones, including hormonal therapies and the asthma-obesity interaction.

Sex differences in breathing

Breathing is a vital behavior that ensures both the adequate supply of oxygen and the elimination of CO₂, and it is influenced by many factors. Despite that most of the studies in respiratory physiology rely heavily on male subjects, there is much evidence to suggest that sex is an important factor in the respiratory control system, including the susceptibility for some diseases. These different respiratory responses in males and females may be related to the actions of sex hormones, especially in adulthood. These hormones affect neuromodulatory systems that influence the central medullary rhythm/pontine pattern generator and integrator, sensory inputs to the integrator and motor output to the respiratory muscles. In this article, we will first review the sex dependence on the prevalence of some respiratory-related diseases. Then, we will discuss the role of sex and gonadal hormones in respiratory control under resting conditions and during respiratory challenges, such as hypoxia and hypercapnia, and whether hormonal fluctuations during the estrous/menstrual cycle affect breathing control. We will then discuss the role of the locus coeruleus, a sexually dimorphic CO₂/pH-chemosensitive nucleus, on breathing regulation in males and females. Next, we will highlight the studies that exist regarding sex differences in respiratory control during development. Finally, the few existing studies regarding the influence of sex on breathing control in non-mammalian vertebrates will be discussed.

Female-specific risk factors associated with risk of ACO (asthma COPD overlap) in aboriginal people

Objective: Sex differences in incidence, susceptibility and severity of many chronic respiratory diseases have been long recognized. Asthma-COPD Overlap (ACO) is newly recognized disease with its management guidelines reported in 2015. The objective of this analysis is to identify the female-specific risk factors associated with ACO in Aboriginal people.Methods: The Aboriginal Peoples Survey 2012 (N = 28,410) is the fourth cycle of a national cross-sectional survey representative of the First Nations living off reserve, Metis and Inuit. The 2012 APS collected information on employment, education, health status, housing, family background and income. Survey Logistic Regression was used to identify the significant risk factors for ACO in the multivariate analysis.Results: The prevalence of ACO was 1.65% and 3.53% in males and females, respectively. The following factors were significantly associated with increased risk of ACO in both males and females: increased age, living in Quebec, living in a rented dwelling and dwelling in need of major repairs. However, four factors including marital status (being widowed, separated, or divorced), smoking status (being a current daily smoker), having a diagnosis of diabetes and working 40 h and over a week were significantly associated with increased risk of ACO in females not males.Conclusion:The results of our study may offer useful evidence for future development of female-specific prevention and public health intervention programs in aboriginal communities to reduce the burden of ACO.

Risk of asthma onset after natural and surgical menopause: Results from the French E3N cohort

BACKGROUND

The gender switch in asthma incidence around puberty has been put forward to suggest a role of sex hormones in asthma. However, there are limited and inconsistent findings on change in asthma incidence with menopause. We aimed to investigate the associations between menopause and asthma incidence, and interactions with overweight/obesity.

METHODS

Asthma incidence was assessed in 67,872 women free of asthma at baseline (aged 41-68 years) and regularly followed up as a part of the French E3N cohort. Adjusted hazard ratios (aHR) were derived from Cox models considering age as the time-scale, menopausal status as a time-varying covariate and taking into account menopausal treatment.

RESULTS

During 843,243 person-years of follow-up, 1205 new-onset asthma cases were identified. Compared with pre-menopause, surgical menopause was associated with an increased risk of asthma onset (aHR = 1.33 [95%CI 1.01-1.75]) but no association was observed for natural menopause (aHR = 1.05 [0.84-1.32]). In women with natural menopause, a further analysis separating the transition through menopause and the later post-menopausal period did not show any change in asthma incidence with menopause in the total sample or in normal-weight women alone. However, in overweight/obese women, peri-menopausal and post-menopausal women had an increased risk of developing asthma compared with pre-menopausal women of the same age (aHR = 1.91 [1.00-3.66] and aHR = 2.08 [1.07-4.06] respectively).

CONCLUSION

Surgical menopause was associated with an increased risk of asthma onset. For natural menopause, no change in asthma incidence was observed in normal-weight women. However, overweight/obese women had an increased risk of developing asthma after natural menopause.

Asthma Over the Age of 65: All's Well That Ends Well

Asthma in older adults (often classified as those 65 years or older) is relatively common, underdiagnosed, and suboptimally treated. It is an important health problem, as the population of the United States continues to age. Unfortunately, asthma morbidity and mortality rates are highest in this age group. Alterations in the innate and adaptive immune responses occur with aging, and contribute to pathophysiologic differences and subsequent treatment challenges. The symptoms of asthma may differ from those in younger populations, and often include fatigue. There are unique factors that can complicate asthma management among older adults, including comorbidities, menopause, caregiver roles, and depression. Pharmacologic therapies are often not as effective as in younger populations, and may have greater side effects. Spirometry, peak flow measurements, and asthma education are typically underused, and may contribute to delays in diagnosis as well as worse outcomes. There are specific strategies that health care providers can take to improve the care of older adults with asthma.

High Prevalence of Asthma in Elderly Women: Findings From a Korean National Health Database and Adult Asthma Cohort

Purpose

The prevalence and burden of asthma is increasing worldwide. In this study, we analyzed 3 different Korean national health survey datasets to determine the general features of adult asthma in Korea and to obtain basic information that would support future strategies for better management of adult asthma.

Methods

The surveys used in this study included the Korea National Health and Nutrition Examination Survey (KNHANES), Korea Community Health Survey (KCHS) and National Health Insurance Service-National Sample Cohort (NHIS-NSC). We investigated annual asthma prevalence, evaluating the rate and risk factors of asthma exacerbation by age and sex, and clinical data of 1,832 patients with asthma who were registered in the Cohort for Reality and Evolution of Adult Asthma in Korea (COREA) were analyzed to elucidate risk factors for asthma exacerbation. We also analyzed another asthma cohort and added it as replication data.

Results

In the KNHANES database, annual asthma prevalence rates varied from 1.2% to 3.1%. In the KCHS database, overall prevalence increased, with significant regional differences (1.6%–2.1%). The NHIS-NSC indicated a gradual increase in annual asthma prevalence from 4.5% to 6.2%. Interestingly, all 3 surveys indicated the highest prevalence of asthma among elderly women. In addition, elderly women with asthma had a significantly higher risk of asthma exacerbation (odds ratio [OR], 1.87; 95% confidence interval [CI], 1.19–2.93; P=0.006). Approximately 11% of patients were classified as having severe asthma. An asthma cohort analysis identified female sex, low baseline pulmonary function, longer treatment duration, high variability in pulmonary function and significant changes in Asthma Control Test scores as risk factors for asthma exacerbation.

Conclusions

The prevalence of asthma in Korea is consistently high among elderly and female populations. These results should lay the foundation for strategies for effective asthma prevention and management; elderly female patients with asthma should receive particular attention.

Menopausal asthma-much ado about nothing? An observational study

OBJECTIVE

Menopausal asthma is considered a distinct asthma phenotype. Our aim was to identify potential specific features of asthma in postmenopausal women in a cohort of Polish females.

METHODS

Asthma severity and control, pulmonary function, exhaled nitric oxide (FE_NO), peripheral blood and induced sputum (IS) differential cell count were compared in three groups: women with premenopausal asthma (group 1), menopausal women with pre-existing asthma (group 2A) and menopausal women with asthma onset in the perimenopausal or menopausal period (group 2B).

RESULTS

We enrolled 27 women to group 1, 13 to group 2A and 16 to group 2B. Asthma severity and control, blood eosinophil count and FE_NO did not differ among the groups. Menopausal women had a higher incidence of irreversible airway obstruction (84.6% in group 2A and 56.2% in group 2B vs. 22.2% in group 1, p < 0.001 and p = 0.03, respectively). The proportion of patients with sputum eosinophilia was highest in menopausal women with pre-existing asthma, although the difference did not reach statistical significance (88.9% in group 2A vs. 66.7% in group 2B and 65.0% in group 1, respectively, p = 0.86).

CONCLUSIONS

Menopausal women with asthma are characterized by an increased incidence of irreversible airway obstruction regardless of disease duration. This may indicate that age may contribute to pulmonary function impairment in asthmatic women independently of their hormonal status at the time of asthma diagnosis. Our results failed to confirm the presence of specific asthma features which would allow to distinguish the phenotype of menopausal asthma.

Prophylactic Supplementation of Bifidobacterium longum 51A Protects Mice from Ovariectomy-Induced Exacerbated Allergic Airway Inflammation and Airway Hyperresponsiveness

Asthma is a chronic inflammatory disease that affects more females than males after puberty, and its symptoms and severity in women change during menstruation and menopause. Recently, evidence has demonstrated that interactions among the microbiota, female sex hormones, and immunity are associated with the development of autoimmune diseases. However, no studies have investigated if therapeutic gut microbiota modulation strategies could affect asthma exacerbation during menstruation and menopause. Here we aimed to examine the preventive effects of a probiotic, Bifidobacterium longum 5^1A, on airway inflammation exacerbation in allergic ovariectomized mice. We first evaluated the gut microbiota composition and diversity in mice 10 days after ovariectomy. Next, we examined whether re-exposure of ovariectomized allergic mice to antigen (ovalbumin) would lead to exacerbation of lung inflammation. Finally, we evaluated the preventive and treatment effect of B. longum 5^1A on lung inflammation and airway hyperresponsiveness. Our results showed that whereas ovariectomy caused no alterations in the gut microbiota composition and diversity in this animal model, 10 days after ovariectomy, preventive use administration of B. longum 5^1A, rather than its use after surgery was capable of attenuate the exacerbated lung inflammation and hyperresponsiveness in ovariectomized allergic mice. This prophylactic effect of B. longum 5^1A involves acetate production, which led to increased fecal acetate levels and, consequently, increased Treg cells in ovariectomized allergic mice.

Menopause Is Associated with Accelerated Lung Function Decline

RATIONALE

Menopause is associated with changes in sex hormones, which affect immunity, inflammation, and osteoporosis and may impair lung function. Lung function decline has not previously been investigated in relation to menopause.

OBJECTIVES

To study whether lung function decline, assessed by FVC and FEV₁, is accelerated in women who undergo menopause.

METHODS

The population-based longitudinal European Community Respiratory Health Survey provided serum samples, spirometry, and questionnaire data about respiratory and reproductive health from three study waves (n = 1,438). We measured follicle-stimulating hormone and luteinizing hormone and added information on menstrual patterns to determine menopausal status using latent class analysis. Associations with lung function decline were investigated using linear mixed effects models, adjusting for age, height, weight, pack-years, current smoking, age at completed full-time education, spirometer, and including study center as random effect.

MEASUREMENTS AND MAIN RESULTS

Menopausal status was associated with accelerated lung function decline. The adjusted mean FVC decline was increased by -10.2 ml/yr (95% confidence interval [CI], -13.1 to -7.2) in transitional women and -12.5 ml/yr (95% CI, -16.2 to -8.9) in post-menopausal women, compared with women menstruating regularly. The adjusted mean FEV₁ decline increased by -3.8 ml/yr (95% CI, -6.3 to -2.9) in transitional women and -5.2 ml/yr (95% CI, -8.3 to -2.0) in post-menopausal women.

CONCLUSIONS

Lung function declined more rapidly among transitional and post-menopausal women, in particular for FVC, beyond the expected age change. Clinicians should be aware that respiratory health often deteriorates during reproductive aging.

Association between asthma and female sex hormones

CONTEXT AND OBJECTIVE:

The relationship between sex hormones and asthma has been evaluated in several studies. The aim of this review article was to investigate the association between asthma and female sex hormones, under different conditions (premenstrual asthma, use of oral contraceptives, menopause, hormone replacement therapy and pregnancy).

DESIGN AND SETTING:

Narrative review of the medical literature, Universidade Federal do Tocantins (UFT) and Universidade Federal de São Paulo (Unifesp).

METHODS:

We searched the CAPES journal portal, a Brazilian platform that provides access to articles in the MEDLINE, PubMed, SciELO, and LILACS databases. The following keywords were used based on Medical Subject Headings: asthma, sex hormones, women and use of oral contraceptives.

RESULTS:

The associations between sex hormones and asthma remain obscure. In adults, asthma is more common in women than in men. In addition, mortality due to asthma is significantly higher among females. The immune system is influenced by sex hormones: either because progesterone stimulates progesterone-induced blocking factor and Th2 cytokines or because contraceptives derived from progesterone and estrogen stimulate the transcription factor GATA-3.

CONCLUSIONS:

The associations between asthma and female sex hormones remain obscure. We speculate that estrogen fluctuations are responsible for asthma exacerbations that occur in women. Because of the anti-inflammatory action of estrogen, it decreases TNF-α production, interferon-γ expression and NK cell activity. We suggest that further studies that highlight the underlying physiopathological mechanisms contributing towards these interactions should be conducted.

The impact of parity and age at first and last childbirth on the prevalence of delayed-onset asthma in women: The Korean National Health and Nutrition Examination Survey

OBJECT

Asthma is a chronic inflammatory airway disease. The aim of this study was to investigate the relationships between asthma and reproductive factors, including age at first childbirth and parity, in a representative sample of Korean women.

MAIN OUTCOME MEASURES

We analyzed data from the Korean National Health and Nutrition Examination Survey (2010-2012). A total of 7837 adults who completed a questionnaire and examination were evaluated. The presence of asthma was based on the Health Interview Survey. Reproductive factors were estimated by trained interviewers using participant recall.

RESULTS

The women with asthma were significantly older than those without asthma. BMI, hypertension, education level, income level, occupation, alcohol consumption, and age at menarche and first birth were significantly associated with the diagnosis of asthma. Higher parity was positively associated with later-onset asthma. In addition, women who were younger at first birth had a greater prevalence of later-onset asthma. After controlling for confounders, being aged under 20 at first birth was significantly associated with an asthma diagnosis compared with women aged 25-29 at first birth (OR [95% CI]: 1.81 [1.14-2.89]).

CONCLUSIONS

Although higher parity was associated with asthma in women, its significance disappeared after adjustment. These results warrant future studies to explore the mechanisms responsible for the association between reproductive factors and asthma.

Estrogen replacement therapy and asthma

A growing body of clinical and experimental evidence indicates that female sex hormones, particularly estrogen, have significant effects on normal airway function as well as on respiratory disorders, such as asthma. These effects are very complex and are exerted at several levels, directly on airway reactivity or indirectly through regulation of the immune and inflammatory responses in the lung. They can have relevant clinical implications not only according to the phases of the reproductive life in women, but also in relation to the therapeutical administration of estrogen, as in the case of menopausal hormone therapy. Clinical evidence suggests that administration of estrogen to menopausal women is associated with increased rates of newly diagnosed asthma. Conversely, functional studies show that estrogen can improve objective indexes of respiratory functionality.

Incidence and risk factors for exacerbations of asthma during pregnancy

Background

Asthma is one of the most common chronic diseases among pregnant women. Acute exacerbations of asthma during pregnancy have an unfavorable impact on pregnancy outcome. This review provides an overview of current knowledge of incidence, mechanisms, and risk factors for acute exacerbations of asthma during pregnancy.

Methods

A narrative literature review was carried out using the PubMed database.

Results

During pregnancy, up to 6% of women with asthma are hospitalized for an acute exacerbation. The maternal immune system is characterized by a very high T-helper-2:T-helper-1 cytokine ratio during pregnancy and thereby provides an environment essential for fetal survival but one that may aggravate asthma. Cells of the innate immune system such as monocytes and neutrophils are also increased during pregnancy, and this too can exacerbate maternal asthma. Severe or difficult-to-control asthma appears to be the major risk factor for exacerbations during pregnancy, but studies also suggest that nonadherence with controller medication and viral infections are important triggers of exacerbations during pregnancy. So far, inconsistent findings have been reported regarding the effect of fetal sex on exacerbations during pregnancy. Other risk factors for exacerbation during pregnancy include obesity, ethnicity, and reflux, whereas atopy does not appear to be a risk factor.

Discussion

The incidence of asthma exacerbations during pregnancy is disturbingly high. Severe asthma – better described as difficult-to-control asthma – nonadherence with controller therapy, viral infections, obesity, and ethnicity are likely to be important risk factors for exacerbations of asthma during pregnancy, whereas inconsistent findings have been reported with regard to the importance of sex of the fetus.

Association between allergies, asthma, and breast cancer risk among women in Ontario, Canada

PURPOSE

To investigate the association between allergies, asthma, and breast cancer risk in a large, population-based case-control study.

METHODS

Breast cancer cases (n = 3,101) were identified using the Ontario Cancer Registry and population controls (n = 3,471) through random digit dialing. Self-reported histories of allergies, hay fever, and asthma were collected by questionnaire. Logistic regression was used to assess associations between breast cancer risk and history of allergy/hay fever and asthma, with 16 possible confounders examined. Analyses were stratified by menopausal status.

RESULTS

A history of allergies or hay fever was associated with a small reduction in breast cancer risk [age-adjusted odds ratio (AOR) = 0.86, 95 % confidence interval (CI) 0.77-0.96] and did not differ by menopausal status. Asthma was not associated with breast cancer risk overall; however, among premenopausal women, asthma was associated with a reduced risk of breast cancer (AOR = 0.72, 95 % CI 0.54-0.97).

CONCLUSIONS

A history of allergies may be associated with a modest reduction in breast cancer risk. Asthma does not appear to be associated with breast cancer risk overall; however, asthma may be associated with reduced breast cancer risk among premenopausal women.