Effect of sex of fetus on asthma during pregnancy: blind prospective study

Sex differences in innate and adaptive immunity impact fetal, placental, and maternal health†

The differences between males and females begin shortly after birth, continue throughout prenatal development, and eventually extend into childhood and adult life. Male embryos and fetuses prioritize proliferation and growth, often at the expense of the fetoplacental energy reserves. This singular focus on growth over adaptability leaves male fetuses and neonates vulnerable to adverse outcomes during pregnancy and birth and can have lasting impacts throughout life. Beyond this prioritization of growth, male placentas and fetuses also respond to infection and inflammation differently than female counterparts. Pregnancies carrying female fetuses have a more regulatory immune response, whereas pregnancies carrying male fetuses have a stronger inflammatory response. These differences can be seen as early as the innate immune response with differences in cytokine and chemokine signaling. The sexual dimorphism in immunity then continues into the adaptive immune response with differences in T-cell biology and antibody production and transfer. As it appears that these sex-specific differences are amplified in pathologic pregnancies, it stands to reason that differences in the placental, fetal, and maternal immune responses in pregnancy contribute to increased male perinatal morbidity and mortality. In this review, we will describe the genetic and hormonal contributions to the sexual dimorphism of fetal and placental immunity. We will also discuss current research efforts to describe the sex-specific differences of the maternal-fetal interface and how it impacts fetal and maternal health.

The obstetric aspects of maternal asthma

Asthma is the commonest chronic medical condition encountered in pregnancy. Poor asthma control and exacerbations are frequently encountered due to treatment non-adherence, pregnancy-related aggravating factors such as increased susceptibility to viral infections, and comorbidities that are commonly associated. Asthma-related inflammatory reactions and placental effects, the effect of medications, and respiratory symptoms and hypoxia are probably to interact to result in an increased adverse obstetric outcomes including miscarriage, foetal congenital anomalies, pregnancy hypertensive disorders, gestational diabetes, preterm labour and birth, antepartum haemorrhage, low birthweight and foetal growth restriction (FGR), caesarean delivery, postpartum haemorrhage (PPH), maternal intensive care admission, and even mortality, while the offspring also has increased long-term morbidity. Interdisciplinary management with frequent assessment by symptoms, spirometry, and biomarkers, together with removal of risk factors such as smoking and appropriate instigation of treatment including short courses of systemic corticosteroid, could ensure optimal and tailored treatment to control symptoms, prevent exacerbations, and ultimately enhancing maternal and perinatal outcomes.

Risk factors for asthma exacerbation during pregnancy: protocol for a systematic review and meta-analysis

BACKGROUND

Asthma is the most common medical condition to affect pregnancy. Asthma exacerbations occur in up to 45% of pregnant women and have been associated with adverse perinatal and infant outcomes. Conflicting literature exists regarding the risk factors for exacerbations, and no synthesis of the literature currently exists. Therefore, this systematic review and meta-analysis aims to determine risk factors for asthma exacerbations during pregnancy among pregnant women with asthma.

METHODS

This protocol has been reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis protocols checklist. A systematic search will be conducted in the electronic MEDLINE, Embase, CINAHL and Cochrane Clinical Trials Register databases (from January 2000 onwards). Eligibility of each publication will be determined based on predefined selection criteria. Prospective cohort studies, retrospective cohort studies, case-control studies and randomised controlled trials (RCTs) will be included. Quality of included studies will be determined using the Newcastle Ottawa Scale and the Cochrane Risk of Bias tool. Pooled relative risk will be computed using random-effects meta-analyses. Heterogeneity will be assessed using the chi-squared test and the I2 parameter. Publication bias will be assessed by inspecting a funnel plot for asymmetry and with the Egger's test of analyses including ten studies or more.

DISCUSSION

The results of this systematic review and meta-analysis will discuss the potential risk factors for asthma exacerbations during pregnancy. This may aid healthcare professionals in early identification of pregnant women with asthma at risk of poor outcomes, providing the opportunity to implement early interventions in order to avoid deterioration of asthma symptoms during pregnancy.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020196190.

Sex Disparities in Asthma Development and Clinical Outcomes: Implications for Treatment Strategies

A gender-related disparity exists in asthma morbidity and mortality, which shifts at around puberty from a male predominance to a female predominance. This is clinically reflected in the fact that asthma that occurs in childhood (childhood-onset asthma) mainly affects boys, and that asthma that occurs in adulthood (adult-onset asthma) mainly affects women. Adult-onset asthma is often non-atopic, more severe, and associated with a poorer prognosis, thus posing a marked burden to women’s health and healthcare system. Many factors have been indicated to explain this gender-related disparity, including sociocultural and environmental factors as well as biological sex differences (genetic, pulmonary and immunological factors). It has long been suggested that sex hormones may be implicated in at least these biological sex differences. Overall, the evidence remains equivocal for the role of most sex hormones in asthma pathogenesis and clinical outcomes. Well-designed randomized clinical trials are required assessing the potential preventive or therapeutic effects of hormonal contraceptives on asthma in women, thereby helping to advance the evidence to inform future practice guidelines. The mechanisms underlying the role of sex hormones in asthma are complex, and our understanding is not yet complete. Additional mechanistic studies elucidating sex hormone signaling pathways and their interactions involved in the pathogenesis and clinical manifestations of asthma will help to identify potential sex hormone-driven asthma endotypes and novel therapeutic targets, providing the basis for a more personalized asthma management strategy.

Role of Sex Hormones at Different Physiobiological Conditions and Therapeutic Potential in MBD2 Mediated Severe Asthma

Sex hormone has become a “hot topic” to evaluate the hormonal therapeutic potential in severe asthma. Th17 cell is one of the main influencing factors involved in the pathogenesis of severe asthma, hence also called as kernel of severe asthma, and Th17 subtype of non-T2 asthma is less responsive (resistance) to inhaled corticosteroid (ICS), so severe in nature. Methyl-CpG binding domain protein 2 (MBD2) is overexpressed and regulates the Th17 differentiation, showing the possibility of therapeutic target in treating Th17 mediated severe asthma. Sex hormone fluctuates at the different physiobiological conditions of the human body and affects the asthma pathobiology showing its role in asthma prevalence, severity, remission, and therapy. This review briefly overviews the sex hormones, their influence in asthma at the different physiobiological conditions of human body, and MBD2 severe asthma connection with the possible therapeutic potential of sex steroids in MBD2 mediated Th17 predominant severe asthma. Male sex hormone tends to show a beneficial effect and possibly downregulates the expression of Th17 cells via regulating MBD2 through a mechanism distinct from corticosteroid treatment and guides us towards discovery of new therapeutic agent, reduces the asthma-related complications, and promotes long-term survival by lowering the risk of therapy-resistant issues of old age severe asthma.

Pharmacotherapeutic management of asthma in pregnancy and the effect of sex hormones

INTRODUCTION

Asthma is a common medical condition that can frequently affect pregnancy, and thus optimal management of asthma in pregnancy is important for both mother and baby. This article reviews recent developments of asthma pharmacotherapy and provides emerging data on the safety of asthma controller medications and biological therapies in pregnancy. The authors highlight the clinical outcomes of asthma during pregnancy, and summarize emerging new data related to the influence of sex hormones and fetal sex on asthma severity.

AREAS COVERED

This review of asthma pharmacotherapy during pregnancy examines the recent guidelines and reports the most pertinent publications on safety data and asthma management.

EXPERT OPINION

Asthma management during pregnancy follows the same principles as that of non-pregnant asthma. The available data for most asthma medications are reassuring, however there is a lack of adequate safety data available because pregnant women are generally excluded from clinical trials. More clarity is needed in guidelines regarding the management of asthma in pregnancy, and high-quality randomized control trials are required to strengthen the evidence base and inform future guidelines. In particular, safety studies examining biological therapies in pregnant women with severe asthma are needed.

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.

Alterations in the Maternal Peripheral Microvascular Response in Pregnancies Complicated by Preeclampsia and the Impact of Fetal Sex

OBJECTIVE

Peripheral microvascular function is altered in preeclampsia (PE). Recent studies suggest that maternal physiology varies with fetal sex. We wanted to examine if there were sex-specific differences in maternal peripheral microvascular function in normal pregnancy and pregnancy complicated by PE.

METHODS

Peripheral microvascular responses were examined using the noninvasive technique of laser Doppler flowmetry in normotensive healthy pregnant women and in women diagnosed with PE. We measured baseline perfusion, response to thermal hyperemia, post-occlusive reperfusion, and vasodilatation in response to corticotropin-releasing hormone (CRH), a potent vasodilator in human skin.

RESULTS

At 31 to 40 weeks' gestation those women with a male fetus exhibited increased vasodilatation in response to CRH (P <.05) and greater baseline perfusion (P <.05) than those pregnant with a female fetus. PE women pregnant with a male fetus demonstrated a significantly reduced vasodilatation in response to CRH (P <.05), reduced baseline perfusion (P <.05), and reduced response to thermal hyperemia (P <.05) compared to normotensive women pregnant with a male fetus. Microvascular function was not significantly different between preeclamptic and normotensive women with a female fetus.

CONCLUSION

These data show that there are differences in maternal peripheral microvascular function in relation to fetal sex.

Asthma is Different in Women

Gender differences in asthma incidence, prevalence and severity have been reported worldwide. After puberty, asthma becomes more prevalent and severe in women, and is highest in women with early menarche or with multiple gestations, suggesting a role for sex hormones in asthma genesis. However, the impact of sex hormones on the pathophysiology of asthma is confounded by and difficult to differentiate from age, obesity, atopy, and other gender associated environmental exposures. There are also gender discrepancies in the perception of asthma symptoms. Understanding gender differences in asthma is important to provide effective education and personalized management plans for asthmatics across the lifecourse.

Asthma in pregnancy

Asthma affects approximately 8% of women during pregnancy. Pregnancy results in a variable course for asthma control, likely contributed to by physiological changes affecting the respiratory, immune, and hormonal systems. While asthma during pregnancy has been associated with an increased risk of maternal and fetal complications including malformations, available data also suggest that active asthma management and monitoring can decrease the risk of adverse outcomes. The diagnosis, disease classification, and goals for asthma management in the pregnant woman are the same as for nonpregnant patients. However, evidence shows that pregnant asthmatics are more likely to be undertreated, resulting in asthma exacerbations occurring in approximately one third and hospitalization in one tenth of patients. Pharmacotherapeutic management of asthma exacerbations in pregnant patients follows standard treatment guidelines. In contrast, the principles of asthma maintenance therapy are slightly modified in the pregnant patient. Patients and practitioners may avoid use of asthma medications due to concern for a risk of fetal complications and malformations. A variable amount of information is available regarding the risk of a given asthma medication to cause adverse fetal outcomes, and it is preferable to use an inhaled product. Nevertheless, based on available data, the majority of asthma medications are regarded as safe for use during pregnancy. And, any increased risk to either the mother or fetus from medication use appears to be small compared to that associated with poor asthma control.

Fetal sex specific differences in human placentation: a prospective cohort study

INTRODUCTION

Our objective was to assess fetal sex specific differences in first trimester placental biomarkers of both physiological and pathological pregnancies and their interaction with environmental influences. This study is embedded in the Generation R Study, a prospective cohort study.

METHODS

Only live singleton births were included. Linear regression was performed to assess the effect of sex on first trimester placental biomarkers. Interaction analyses were performed to assess interaction of fetal sex with environmental influences. First trimester soluble fms-like tyrosine kinase (s-Flt1), placental growth factor (PLGF), plasminogen activator inhibitor (PAI-2) and homocysteine levels were assessed.

RESULTS

Significant fetal sex specific differences in placental biomarkers were observed. S-Flt1, PAI-2 and PLGF log transformated concentrations were 0.08 ng/mL (95% CI 0.05; 0.11), 0.07 ng/mL (95% CI 0.06; 0.09) and 0.04 pg/mL (95% CI 0.01; 0.06) higher in case of female as compared to male placentas. In pregnancies complicated by pre-eclampsia (PE), preterm birth (PTB) or a newborn being small for gestational age (SGA) no fetal sex specific differences were observed. Interaction analyses suggest that concentrations of s-Flt1, PLGF and PAI-2 decrease in male placentas in the case of hyperhomocysteinemia but remain equal in female placentas.

DISCUSSION

Fetal sex affects early placentation processes with discrepancies regarding pregnancies complicated by PE, PTB or a newborn being SGA. This suggests that other mechanisms causing these complications may dominate the fetal sex effect. The differences concerning homocysteine suggest that fetal sex dependent placental gene-environment interactions exist.

CONCLUSION

Fetal sex specific differences in placental biomarkers exist.

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.

Asthma in pregnancy: a review

Asthma is one of the most common medical conditions in women of childbearing age. There are now data to show that asthma is not a benign condition with respect to maternal and fetal health. Despite this there are several problems encountered in the management of such women. There is a tendency to cease or reduce optimal asthma treatments because pregnant women and/or their clinicians may believe they pose a risk to the fetus. There is also a lack of clinician awareness of the complications of asthma in pregnancy.

Management of asthma during pregnancy

The prevalence of asthma in pregnant women appears to be increasing. Recent evidence demonstrates that pregnant asthmatic women with moderate-to-severe asthma may have an increased risk of adverse perinatal outcomes. The goal of asthma management during pregnancy is to optimize maternal and fetal health.

Maternal enterovirus infection as a risk factor for type 1 diabetes in the exposed offspring

OBJECTIVE

Maternal enterovirus infections during pregnancy have been linked to an increased risk of type 1 diabetes in the offspring. The aim of this study was to evaluate this association in a unique series of pregnant mothers whose child progressed to clinical type 1 diabetes.

RESEARCH DESIGN AND METHODS

Maternal and in utero enterovirus infections were studied in 171 offspring who presented with type 1 diabetes before the age of 11 years and in 316 control subjects matched for date and place of birth, sex, and HLA-DQ risk alleles for diabetes. Acute enterovirus infections were diagnosed by increases in enterovirus IgG and IgM in samples taken from the mother at the end of the first trimester of pregnancy and cord blood samples taken at delivery.

RESULTS

Signs of maternal enterovirus infection were observed in altogether 19.3% of the mothers of affected children and in 12.0% of the mothers of control children (P = 0.038). This difference was seen in different HLA risk groups and in both sexes of the offspring, and it was unrelated to the age of the child at the diagnosis of diabetes or the age of the mother at delivery.

CONCLUSIONS

These results suggest that an enterovirus infection during pregnancy is not a major risk factor for type 1 diabetes in childhood but may play a role in some susceptible subjects.

Review: The feto-placental unit, pregnancy pathology and impact on long term maternal health

Pregnancy induces a number of alterations to maternal physiology to accommodate the increased demands made by the developing fetus and placenta. These alterations appear at least in part to be driven by products derived from the feto-placental unit, including microchimeric cells, as well as placental exosomes and microparticles, inducing changes to maternal physiology both during pregnancy and beyond. Further, increasing evidence suggests that some of these alterations are dependent on the sex of the fetus. Pre-eclampsia and asthma represent two common pregnancy complications that have provided valuable insight into how the feto-placental unit influences maternal physiology in a sex-specific manner. Pregnancy-induced alterations in maternal physiology may expose pre-existing subclinical pathologies and provide insight into future maternal health and disease. While most pregnancy-induced alterations to the maternal system are reversed following delivery, some can persist after parturition leading to cardiovascular, metabolic and autoimmune disease and increased risk of early mortality.

[Exacerbations of asthma in pregnant women]

Prevention of exacerbations and effective treatment is essential in pregnant asthmatic women. The management is well documented. Misunderstanding of the recommendations leads to unsuitable, insufficient treatment and is responsible for more frequent recurrences in the pregnant woman compared with the non pregnant. Above all, good control of the disease and the prevention of exacerbations, based on inhaled corticosteroid therapy and smoking cessation, reduces complications, in particular prematurity and low birth weight.

Asthma in pregnancy

Worldwide the prevalence of asthma among pregnant women is on the rise, and pregnancy leads to a worsening of asthma for many women. This article examines the changes in asthma that may occur during pregnancy, with particular reference to asthma exacerbations. Asthma affects not only the mother but the baby as well, with potential complications including low birth weight, preterm delivery, perinatal mortality, and preeclampsia. Barriers to effective asthma management and opportunities for optimized care and treatment are discussed, and a summary of the clinical guidelines for the management of asthma during pregnancy is presented.

Asthma in pregnancy: pathophysiology, diagnosis and management

Asthma is a common, potentially serious, even life-threatening, chronic medical condition seen amongst nearly all groups of patients, regardless of ethnicity and socioeconomic circumstances. This article addresses the group of pregnant women with symptomatic asthma as well as those whose asthma is asymptomatic as a result of good control. The incidence, the pathophysiologic changes of pregnancy, and the interplay between these changes and asthma are reviewed in this article. The classification of these patients and appropriate management strategies are discussed.

Asthma and pregnancy: a review of two decades

The prevalence of asthma among pregnant women varies among studies from 4 to 8%, making it by far the most common respiratory disorder complicating pregnancy. Controversy exists among the numerous retrospective and prospective studies regarding pregnancy outcomes of asthmatic patients. Overall, the literature indicates that women with severe asthma are at an increased risk for preterm delivery, low birth weight, preeclampsia and Caesarean delivery, especially in the absence of inhaled corticosteroid therapy. Asthmatic women carrying a female fetus may particularly be at increased risk of these adverse outcomes. On the other hand, mild or moderate, well-controlled asthma is associated with favorable pregnancy and perinatal outcomes. Pregnancy also influences the course of asthma. Recently published data indicate that the real risk for an exacerbation during pregnancy may be underestimated. There is no question, however, that the risk of having an exacerbation correlates closely with the severity of asthma. The mechanisms responsible for these changes are not fully understood. Maternal hypoxia or inflammatory processes have been suggested and could explain reduced fetal growth through alterations in placental function. The goal of asthma therapy is to maintain adequate oxygenation of the fetus by prevention of exacerbations. Optimal management of asthma during pregnancy should include scheduled monitoring of objective lung function tests, avoiding triggers, patient education and tailored pharmacologic therapy. Inhaled corticosteroids are the treatment of choice for all levels of persistent asthma, yet other drug classes, such as beta(2)-agonists and theophylline, are effective and safe for use during pregnancy.

Maternal and neonatal outcomes of pregnancies complicated by asthma in an Australian population

OBJECTIVE

To determine if there are sex differences in risk and incidence of stillbirth, preterm delivery and small-for-gestational age (SGA) in pregnancies complicated by maternal asthma relative to a non-asthmatic population.

STUDY DESIGN

Univariant and multiple regression analysis of the incidence of preterm delivery, SGA and stillbirth in singleton pregnancies complicated by asthma in Newcastle, NSW, Australia, from 1995 to 1999.

RESULTS

Asthma complicated 12% of all singleton pregnancies. The incidence of preterm delivery was not significantly different between asthmatic (13%) and non-asthmatic (11%) pregnancies. Male fetuses (53%) were more likely to deliver preterm than female fetuses (47%) in both asthmatic and non-asthmatic populations. There were significantly more male neonates of pregnancies complicated by asthma that were SGA at term relative to those of the non-asthmatic population. There were significantly more preterm female neonates that were SGA in pregnancies complicated by asthma relative to those of the non-asthmatic population. Male fetuses were more likely to be associated with a stillbirth in pregnancies complicated by asthma than female fetuses.

CONCLUSION

The presence of maternal asthma during pregnancy increases the risk of stillbirth for the male fetus and is associated with changes in fetal growth, but does not increase the incidence of a preterm delivery.

Serum level of immunoglobulin E during pregnancy - does offspring sex matter?

We assessed maternal serum levels of total immunoglobulin E (IgE) in the first, second and third trimester and changes in total IgE levels from first to third trimester in relation to offspring sex. Within a cohort of 29 948 pregnant women, 392 women without a history of pre-eclampsia and with a liveborn child were randomly selected. Information on offspring sex was obtained through linkage to the Medical Birth Registry of Norway. Blood samples from each trimester were analysed for total IgE concentration. Differences in mean levels according to offspring sex were estimated and changes in total IgE levels from first to third trimester were assessed. In all three trimesters there was a tendency of women carrying a male fetus to have a higher mean total IgE level, but significant statistical differences were not reached. The total IgE concentration decreased during pregnancy, but the decrement was less in women carrying a male fetus compared with those who carried a female fetus.

[Asthma and pregnancy. Review of the current literature and management according to the GINA 2006-2007 guidelines]

INTRODUCTION

Many pregnant women are asthmatics and maternal asthma is a source of questions and complications concerning both the progress of the pregnancy itself and the impact on the foetus. In this situation good asthma control is essential as the disease can deteriorate with acute exacerbations, possibly precipitated by reduction or even withdrawal of treatment on account of fear of teratogenicity.

BACKGROUND

Even though asthma treatments are not totally harmless during pregnancy, their use has been validated by several studies and guidelines. To help clinicians, we undertake here a review of the complications induced by maternal asthma and its medications, and then suggest management guidelines according to the most recent publications.

CONCLUSIONS

The risks and benefits of asthma treatments should be explained in a real partnership between the patient and her general practitioner and specialists (obstetrician, chest physician or allergist). In order to reduce complications to both mother and child, perfect control of asthma is required and inhaled steroids remain the treatment of choice for partially or uncontrolled asthma in the pregnant woman.

Effect of fetal gender on maternal asthma exacerbations in pregnant asthmatic women

Recent studies have found that asthmatic women pregnant with a female fetus reported more symptoms and had slightly lower lung function than women pregnant with a male fetus. In order to further investigate this association, we studied the effect of fetal sex on maternal asthma exacerbations and the use of asthma medications during pregnancy. A large cohort of pregnant asthmatic women and their babies was reconstructed between 1990 and 2002 from the linkage of three administrative databases of the Canadian province of Quebec. Asthma exacerbations were defined as a filled prescription of oral corticosteroids, an emergency department visit, or a hospitalization for asthma. Women pregnant with a female fetus were compared to women with a male fetus with respect to their rate of asthma exacerbation, their weekly doses of inhaled short-acting beta(2)-agonists (SABA), and their daily dose of inhaled corticosteroids (ICS) during pregnancy. Logistic and linear regression models were used to obtain effect measures adjusted for several potential confounders such as asthma severity and control prior to pregnancy. The cohort included 5529 pregnancies with a single female fetus and 5728 pregnancies with a single male fetus. No significant differences were found between mothers of a female and male fetus as to the occurrence of asthma exacerbations (adjusted rate ratio=1.02; 95% CI: 0.92-1.14), the daily dose of ICS (adjusted mean difference (AMD): 2.46 microg; 95% CI: -4.01 to 8.93), and the weekly dose of SABA (AMD: 0.004 dose; 95% CI: -0.23 to 0.24). Based on the results, we conclude that fetal gender is unlikely to affect maternal asthma during pregnancy to the point where acute care and medications are more often required among women pregnant with a female fetus.

Fetal sex and maternal asthma control in pregnancy

Asthma is a prevalent chronic disorder that might substantially complicate pregnancy. Some recent reports suggest that the presence of a female fetus might be associated with worse maternal asthma symptoms during pregnancy. We tested this hypothesis using the sample of 719 pregnant women with asthma prospectively enrolled in the OTIS study. The presence of a female fetus was associated with a higher incidence of hospitalizations for asthma during pregnancy (OR = 1.84; 95% CI: 1.05; 3.21) independent of maternal age, BMI, ethnicity, smoking, and socioeconomic status. The current study suggests that pregnant asthmatic women carrying a girl might be more susceptible to asthma exacerbations.

Maternal and cord plasma cytokine and chemokine profile in pregnancies complicated by asthma

The mechanisms contributing to worsening of asthma during pregnancy have not been well characterized. Both asthma and pregnancy are conditions associated with a skewing of the immune response from T helper (Th) 1 toward a Th2 response. We hypothesise that worsening of asthma during pregnancy may be due to an enhanced production of circulating proinflammatory cytokines and chemokines and this may be modified by the use of inhaled glucocorticoid treatment. Peripheral blood was collected from asthmatic (n=35) and control non-asthmatic patients (n=13) in the third trimester (30-37 weeks) of pregnancy. Fetal blood was collected from the umbilical vein of the placenta after delivery from normal (n=24) and pregnancies complicated by asthma (n=24). Plasma samples were assayed for IL-6, -8, eotaxin and RANTES using conventional ELISA. In addition, a range of Th1 and Th2 cytokines measured using Luminex system. There were no significant differences in the levels of maternal IL-6, IL-8, eotaxin and RANTES between asthmatics and nonasthmatics. The results of this study suggest that the presence of asthma does not result in an enhanced circulation of Th2 related cytokines and chemokines during the third trimester of pregnancy. Furthermore peripheral blood cytokine concentrations appear unaffected by inhaled glucocorticoid treatment. Cord plasma eotaxin concentrations were increased in pregnancies complicated by asthma, compared with control. This is the first study to show increased eotaxin production in the feto-placental unit of asthmatic pregnancies and may be one mechanism by which allergy susceptibility is increased in the offspring of asthmatic women.

Effect of maternal asthma and gestational asthma therapy on fetal growth

Asthma is a common chronic condition that might seriously complicate pregnancy and fetal development. This article provides a comprehensive review of the existing literature regarding the effect on fetal growth of maternal asthma and common asthma medications used during pregnancy, including short-and long-acting beta (2)-agonists, inhaled and oral corticosteroids, chromones, leukotriene receptor agonists, and theophylline. Evaluated outcomes of fetal growth include low birth weight, mean birth weight, small for gestational age, birth length and head circumference, and measures of asymmetrical growth retardation. Methodological and practical considerations related to safety of asthma medications in pregnancy and management of gestational asthma are discussed.

Maternal asthma during pregnancy and fetal outcomes: potential mechanisms and possible solutions

PURPOSE OF REVIEW

Asthma exacerbations during pregnancy can be a serious complication that have detrimental consequences for both mother and fetus. The pathophysiological mechanisms that cause worsening asthma during pregnancy are only just starting to be examined. This review will examine the recent literature on immune function in pregnant women, immune function in nonpregnant asthma patients and studies conducted on asthma during pregnancy.

RECENT FINDINGS

Fifty-five percent of women with asthma will experience at least one exacerbation during pregnancy. This has significant effects on fetal growth and survival, especially if the fetus is male. A number of factors that may contribute to the development of worsening asthma during pregnancy include pregnancy-induced changes in maternal immune function, increased maternal susceptibility to infection, female fetal sex, noncompliance with medication and prepregnancy asthma severity. Interestingly, the immune changes in the maternal system in response to the presence of the fetus and placenta are very similar to the immune changes described in nonpregnant asthma patients with noneosinophilic asthma.

SUMMARY

These studies highlight that worsening asthma during pregnancy cannot be attributed to pregnancy alone or asthma alone and may be a complex combination of factors and events.

Is fetal gender associated with emergency department visits for asthma during pregnancy?

BACKGROUND

To investigate if fetal gender (1) affects the risk of having an emergency department (ED) visit for asthma; and (2) is associated with adverse pregnancy outcomes among women who had at least one visit to the ED for asthma during pregnancy.

METHODS

We linked two provincial administrative databases containing records on in-patient deliveries and ED visits. The study sample included women who delivered a live singleton baby between April 2003 and March 2004. Pregnant women who made at least one ED visit for asthma were counted as cases and the rest of the women as control subjects. We performed a multivariable analysis using logistic regression to model the risk of having an ED visit for asthma, with fetal gender being one of the predictors. In addition, a series of multivariable logistic regressions were also constructed separately for cases and controls for the following adverse delivery outcomes: low birth weight baby, preterm delivery, and delivery via Caesarian section.

RESULTS

Among 109,173 live singleton deliveries, 530 women had visited ED due to asthma during pregnancy. While having an ED visit for asthma was positively associated with teenage pregnancy, low income, and presence of pregnancy-induced hypertension, it was not associated with fetal gender (OR 1.01, 95% CI 0.85-1.19). Fetal gender was not a significant predictor of adverse pregnancy outcomes among women who had an asthma ED visit during pregnancy.

CONCLUSION

Fetal gender does not affect the risk of having an ED visit for asthma during pregnancy, and it is not associated with adverse pregnancy outcomes among women who had an asthma-related ED during pregnancy.

Women with asthma: a review of potential variables and preferred medical management

OBJECTIVES

To summarize the potential variables that contribute to the increased risk of asthma in women, outline therapeutic strategies that address these variables, and review current treatment recommendations for both pregnant and nonpregnant women with asthma.

DATA SOURCES

Literature searches (MEDLINE and cross-references) were performed using the keywords asthma and women in combination with the terms compliance, depression, emergency department, hormones, menstruation, mortality, National Asthma Education and Prevention Program, osteoporosis, pregnancy, prevalence, smoking, and treatment. Searches were limited to human studies with data published before 2005.

STUDY SELECTION

The author selected relevant articles for inclusion in this review.

RESULTS

Fluctuations in sex hormones, menstruation, pregnancy, obesity, depression, medication nonadherence, and smoking may contribute to increased asthma symptoms or severity in women. Asthma control may be improved if physicians address conditions and behaviors associated with asthma variability and severity in women. Notably, asthma must be managed aggressively in pregnant women, because uncontrolled asthma can lead to perinatal complications. Asthma treatment in women is optimized through patient and physician adherence to national guideline recommendations, including provision of patient education and asthma action plans.

CONCLUSIONS

Multiple variables throughout the female life cycle may influence asthma control. Successful asthma management requires an ongoing partnership between the patient and her physician to address physiologic (eg, sex hormones, pregnancy, obesity, depression) and nonphysiologic (eg, smoking, medication nonadherence) factors that may contribute to decreased asthma control.

The effect of pregnancy on the course of asthma

The course of asthma is changed by pregnancy in variable ways for unknown reasons. Although the prospective studies used different criteria to stratify the severity of the patients' asthma, their conclusions were remarkably similar. Over-all, an equal number of women have asthma symptoms that improve, worsen, or are unchanged through pregnancy. Asthma symptoms can worsen during pregnancy because of identifiable factors, such as infection, gastroesophageal re-flux disease, reduction of appropriate medications by physician or patient, and smoking. Undertreatment, which remains a problem during pregnancy, can lead to continued difficulty with asthma. Severe asthmatics tend to have increased symptoms compared with mild asthmatics. If symptoms worsen, it usually occurs in the second and third trimesters, with the peak in the sixth month. Generally, there is improvement in asthma in the last 4 weeks of pregnancy. During labor and delivery, only 10% to 20% of asthmatics have symptoms;severe asthmatics are more likely to have exacerbations. Asthma tends to return to the prepregnancy state within 3 months post partum. Successive pregnancies tend to have a similar course in each individual. Every asthmatic woman should be maintained on appropriate medications and followed carefully throughout pregnancy, especially in the second and third trimesters. Asthma specialists should be available for collaborative care when asthma is uncontrolled, or if there is an exacerbation. A timely adjustment in treatment for any changes in asthma course that might occur ensures the best control of the disease in the face of complex multiple influences.

Effect of fetal sex on airway lability in pregnant women with asthma

The authors investigated the association between sex of the fetus and maternal airway lability among pregnant women with asthma. Data were prospectively collected among 702 pregnant women with a diagnosis of asthma who were recruited in southern New England between 1997 and 2000 and followed through pregnancy. Peak expiratory flow lability, defined as percent daily maximum minus the minimum divided by the mean, was assessed at enrollment and at 21, 29, and 37 weeks' gestation. There was a -9.9 percent (95 percent confidence interval: -19.4, -0.4) difference in airway lability observed between women carrying female fetuses and those carrying male fetuses. This difference persisted throughout pregnancy. Among pregnant asthmatic women, carrying a female fetus is associated with worse maternal asthma, as assessed by greater airway lability, than is carrying a male fetus.

Relation between phase of the menstrual cycle and asthma presentations in the emergency department

BACKGROUND

The phase of the menstrual cycle is thought to influence the course of asthma in women. One recent study reported a large increase in exacerbations during the perimenstrual phase, while another found a preovulatory increase. A study was undertaken to determine the relation between phase of the menstrual cycle and acute asthma in patients presenting to the emergency department (ED).

METHODS

All women aged 18-54 years presenting with a diagnosis of acute asthma exacerbation were considered for enrollment in the study. Women who were pregnant, postmenopausal, following hysterectomy, with a >28 day menstrual cycle or incomplete reproductive history were excluded. The 792 eligible women were classified by menstrual phase based on both date of symptom onset and date of ED visit.

RESULTS

When classified by date of symptom onset, 28% were preovulatory (days 5 to 11), 25% were periovulatory (days 12 to 18), 21% were postovulatory (days 19 to 25), and 27% were perimenstrual (days 26 to 4; p = 0.03). When classified by date of ED visit, 28% were preovulatory, 22% were periovulatory, 22% were postovulatory, and 27% were perimenstrual (p = 0.004). Using either approach, there were no significant differences in demographic factors or in asthma severity of women in the various menstrual phase groups.

CONCLUSION

Acute asthma exacerbations do not markedly increase during the perimenstrual phase. The results support the suggestion that both preovulatory and perimenstrual phases are actual triggers of asthma exacerbation in some women, or that these two phases serve as "co-factors" that worsen other recognised triggers of acute asthma.

Sexually dimorphic effects of maternal asthma during pregnancy on placental glucocorticoid metabolism and fetal growth

Human pregnancy is associated with sexually dimorphic differences in mortality and morbidity of the fetus with the male fetus experiencing the poorest outcome following complications such as pre-eclampsia, pre-term delivery and infection. The physiological mechanisms that confer these differences have not been well characterised in the human. Work conducted on the effect of maternal asthma during pregnancy, combining data collected from the mother, placenta and fetus has found some significant sex-related mechanistic differences associated with fetal growth in both normal pregnancies and pregnancies complicated by asthma. Specifically, sexually dimorphic differences have been found in placental glucocorticoid metabolism in male and female fetuses of normal pregnancies. In response to the presence of maternal asthma, only the female fetus alters placental glucocorticoid metabolism resulting in decreased growth. The male fetus does not alter placental function or growth in response to maternal asthma. As a result of the alterations in glucocorticoid metabolism in the female, downstream changes occur in pathways regulated by glucocorticoids. These data suggest that the female fetus adjusts placental function and reduces growth to compensate for maternal disease. However, the male fetus continues to grow in response to maternal asthma with no changes in placental function. This response by the male fetus may partially contribute to the increased risk of morbidity and mortality in this sex.

Severe hypokalaemic paralysis and rhabdomyolysis due to ingestion of liquorice

Chronic ingestion of liquorice induces a syndrome with findings similar to those in primary hyperaldosteronism. We describe a patient who, with a plasma K+ of 1.8 mmol/l, showed a paralysis and severe rhabdomyolysis after the habitual consumption of natural liquorice. Liquorice has become widely available as a flavouring agent in foods and drugs. It is important for physicians to keep liquorice consumption in mind as a cause for hypokalaemic paralysis and rhabdomyolysis.

Acute asthma in pregnancy

Asthma is one of the most common medical conditions that can complicate pregnancy. Although most pregnant women with asthma have controlled disease, some women may experience exacerbation of their disease, necessitating immediate intervention. This article discusses the interrelations between asthma and pregnancy and presents an overview on the management of pregnant women presenting to the hospital with acute severe asthma. Treating physicians must overcome the common belief that pregnant women should not take any medications during pregnancy, and they should keep asthma in pregnant women under control to minimize the risk for maternal and fetal hypoxia.

The change of asthma course during pregnancy

The course of asthma during pregnancy is variable. When the total pregnant asthmatic population is considered, one-third improve, one-third are unchanged, and one-third experience increased symptoms. The course of asthma may be influenced by the many physiologic changes during pregnancy as well as the severity of the pre-existing asthma. Prospective studies have found that severe asthmatics have exacerbations during pregnancy more often than mild asthmatics. The first trimester and the last month of pregnancy are relatively free of exacerbations. The second and third trimesters have more potential for increased asthma symptoms and the need for medications. Change in allergic nasal symptoms may precede similar changes in asthma during pregnancy. The course of asthma during labor and delivery is worsened in only 10% of patients, and their problems are usually mild. Postpartum most women return to their prepregnant state within 3 mo. Physiologic changes in pregnancy affect the pulmonary function with a decrease in functional residual capacity (FRC) and 50% increase in minute ventilation. This change results in hyperventilation in 60-70% of normal pregnancies and a sensation of dyspnea that can be distressing to an asthmatic. There is also nasal congestion in 22-72% of pregnancies beginning in the second trimester, which can also affect asthma. The gastrointestinal system is affected in pregnancy with one-third of women having gastroesophageal reflex disease (GERD). Undertreatment of asthma during pregnancy remains a problem in emergency departments. With awareness of the patient's prepregnant state, careful monitoring during pregnancy will prevent serious exacerbations and complications.

Maternal asthma as a model for examining fetal sex-specific effects on maternal physiology and placental mechanisms that regulate human fetal growth

Studying the effect of maternal asthma during pregnancy on placental function and fetal development has highlighted that there is a strong interaction between mother, placenta and fetus and these interactions appear to be sex-specific. This work has found that the female fetus alters maternal asthma during pregnancy by upregulating maternal inflammatory pathways. When asthma-associated inflammatory pathways are not treated with inhaled steroids during pregnancy, the female fetus has reduced growth and adrenal function due to alterations in placental glucocorticoid metabolism. When the mother uses inhaled steroid for the treatment of her asthma during pregnancy, female fetal growth and placental function are comparable to the control population. The growth of the male fetus appears to be unaffected by asthma or inhaled steroid use. These findings indicate there may be different mechanisms regulating placental glucocorticoid and immune mechanisms depending on fetal sex in both asthmatic and non-asthmatic pregnancies.

Effect of pregnancy and stage of pregnancy on asthma severity: a systematic review

Although pregnancy is purported to affect maternal asthma, the literature has not been reviewed systematically. The purpose of this systematic review was to determine, among pregnant women with asthma, whether pregnancy and stage of pregnancy influence maternal asthma severity. Six electronic databases were searched in January 2003 for prospective studies of currently asthmatic, pregnant women who were enrolled before the third trimester and assessed with objective measures of asthma severity or validated severity scales. Three studies reported 54 pregnant women with asthma who met the inclusion criteria. The most valid study indicated that bronchial hyperresponsiveness to methacholine improved between preconception and pregnancy in 69% of the women, although it deteriorated in 31% of the women. Further, this improvement peaked in the second trimester, reverted after delivery, and was greatest among those women who were most hyperresponsive initially. Lung function also showed a trend towards improvement during pregnancy that was not significant. Large, well-conducted population-based studies that explore different aspects of asthma severity are needed to substantiate these preliminary results.

Maternal asthma is associated with reduced female fetal growth

Asthma during pregnancy is associated with a low birth weight, although the mechanisms contributing to this outcome remain unknown. The relationship between maternal asthma and its treatment, placental function, fetal sex, and low birth weight was examined to establish the effect of asthma on fetal growth. Glucocorticoid intake by women with asthma was assessed throughout pregnancy. The placenta was collected after delivery, and 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) activity was measured. Fetal cortisol and estriol were measured in the umbilical vein plasma at delivery. Those with asthma were compared with a nonasthmatic control group. In women with asthma who did not use inhaled steroids and were pregnant with a female fetus, we observed significantly reduced birth weights, whereas male birth weights were unaffected. The presence of a female fetus was associated with significantly increased maternal circulating monocytes, significantly reduced placental 11beta-HSD2 activity and fetal estriol, and a trend toward elevated fetal plasma cortisol. This study provides evidence that in pregnancies complicated by asthma there is a fetal sex-specific effect on the maternal immune system with adverse effects on placental function and female fetal growth.

Variables affecting asthma course during pregnancy

BACKGROUND

The course of asthma is frequently altered by pregnancy, but the mechanisms remain undefined.

OBJECTIVE

The purpose of this study was to identify specific maternal or pregnancy characteristics that are related to the course of asthma during pregnancy.

METHODS

A secondary analysis of a previous prospective study identified 568 pregnant women whose patient-reported asthma course during pregnancy was compared with the women's usual disease course. Potential explanatory variables were compared between groups defined by their pregnancy versus usual course (better, worse, same).

RESULTS

Improvement of asthma during pregnancy was noted in 33.6%, worsening was reported in 36.3%, no change was reported in 26.4%, and the course was uncertain in 3.7%. There was a significant concordance between asthma course and course of rhinitis during pregnancy. Rhinitis improved in 51.1% of patients whose asthma improved during pregnancy and worsened in 19.8% of these women. Rhinitis worsened in 55.9% of patients whose asthma worsened during pregnancy and improved in 2.1% of these women. No significant relationships were found between gestational asthma course and maternal demographic factors, panic-fear score, smoking, maternal weight, infant birth weight, or infant sex.

CONCLUSIONS

The relationship of gestational asthma course to rhinitis symptoms may have clinical and mechanistic significance. Further studies will be necessary to test this hypothesis.

Pregnancy outcome in asthmatic patients from high altitudes

OBJECTIVE

To compare pregnancy outcome in asthmatic and non-asthmatic patients from high altitudes.

METHOD

A prospective case-control study over a 4-year period. The setting was: Abha Maternity Hospital, south-west region of Saudi Arabia. Eighty-eight asthmatic pregnant patients were followed up on during their pregnancies and deliveries (cases). The control subjects were 106 non-asthmatic patients who delivered during the same period.

RESULTS

There were no statistically significant differences in the mean age, parity and gestation at delivery between the cases and control subjects (P>0.05), while there were statistically significant differences in the mean birth weight, placental weight and number of abortions between the two groups (P<0.05). Antenatal complications occurred in 12.5% of the asthmatic patients and 1.9% of the control subjects. Pre-eclampsia was diagnosed in 7.9% of the asthmatic group but in none of the control subjects. Induction of labor, cesarean section rate, perinatal mortality, congenital malformations and Apgar score <7 at 5 min were significantly higher in the asthmatic patients.

CONCLUSION

Asthma occurring in pregnancy was associated with increased antenatal complications, increased perinatal loss and congenital malformations in our study population.

Asthma in pregnancy

Although about 1% of pregnant women have asthma, it is often underrecognized and suboptimally treated. The course of asthma during pregnancy varies; it improves, remains stable, or worsens in similar proportions of women. The risk of an asthma exacerbation is high immediately postpartum, but the severity of asthma usually returns to the preconception level after delivery and often follows a similar course during subsequent pregnancies. Changes in beta(2)-adrenoceptor responsiveness and changes in airway inflammation induced by high levels of circulating progesterone have been proposed as possible explanations for the effects of pregnancy on asthma. Good control of asthma is essential for maternal and fetal well-being. Acute asthmatic attacks can result in dangerously low fetal oxygenation. Chronically poor control is associated with pregnancy-induced hypertension, preeclampsia, and uterine hemorrhage, as well as greater rates of cesarian section, preterm delivery, intrauterine growth retardation, low birth weight, and congenital malformation. Women with well-controlled asthma during pregnancy, however, have outcomes as good as those in their nonasthmatic counterparts. Inhaled therapies remain the cornerstone of treatment; most appear to be safe in pregnancy.