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Asthma in pregnancy and reproductive health

TL;DR — Good asthma control protects both pregnant person and fetus. Asthma in pregnancy is associated with pre-eclampsia, preterm delivery, fetal growth restriction and low birthweight, but active management attenuates some risks (Murphy 2011, PMID 21749633). Stopping effective inhaled corticosteroid treatment because of pregnancy can expose both patients to greater risk than continuing it. Review control, technique, adherence, smoking, obesity and comorbidity early; use objective lung function when possible; treat attacks promptly; and coordinate respiratory, obstetric and primary care. Safety data are strongest for established inhaled therapies and sparse for newer biologics, so decisions should compare the known risk of uncontrolled disease with the uncertainty of exposure—not compare medication with an imaginary risk-free pregnancy.

Why pregnancy changes asthma care

Pregnancy alters ventilation, oxygen consumption, reflux, nasal congestion and perception of breathlessness. Normal pregnancy can cause dyspnea, but wheeze, variable airflow limitation, nocturnal symptoms and reliever response are not normal physiological findings.

Asthma course is heterogeneous: some improve, some remain stable and some worsen. Previous severity and attacks are more useful than folklore about a “rule of thirds.” Reviews emphasize that asthma remains the most common chronic respiratory disorder complicating pregnancy and needs active, not deferred, management (Colas 2024, PMID 38477324; Bravo-Solarte 2023, PMID 36719688).

Outcomes: association is not destiny

A meta-analysis of 40 publications and 1,637,180 pregnancies associated maternal asthma with:

Outcome Relative risk (95% CI)
Low birthweight 1.46 (1.22–1.75)
Small for gestational age 1.22 (1.14–1.31)
Preterm delivery 1.41 (1.22–1.61)
Pre-eclampsia 1.54 (1.32–1.81)

With active asthma management, excess preterm-delivery risk was no longer statistically significant, RR 1.07 (95% CI 0.91–1.26), although subgroup comparisons cannot prove that management eliminated every confounder (Murphy 2011, PMID 21749633).

A later cohort meta-analysis found increased risks of pregnancy-induced hypertension, RR 1.45 (95% CI 1.29–1.63), and pre-eclampsia, RR 1.43 (1.31–1.57) (Wang 2020, PMID 31762345). Clinical teams should therefore monitor blood pressure and obstetric growth indicators without implying that asthma inevitably causes complications.

Observed outcomes reflect disease activity, hypoxemia, inflammation, smoking, obesity, social conditions, medication changes and surveillance. Confounding by indication is central: patients receiving systemic steroids or biologics usually have more severe disease than untreated comparators.

Preconception and first review

Domain Action
Diagnosis Preserve objective evidence; reconsider mimics if symptoms atypical
Control/risk Record symptoms, night waking, reliever use, lung function and prior attacks
Treatment Confirm actual drugs, dose, device, adherence and access
Exposures Stop smoking/vaping; address household and occupational triggers
Comorbidity Review obesity, rhinitis, reflux, anxiety/depression and sleep disorder
Prevention Vaccination per local pregnancy guidance; written action plan
Coordination Identify respiratory/primary and obstetric leads and urgent-care pathway

Pregnancy should be discussed before conception when possible, but an unplanned pregnancy is not a reason for abrupt controller withdrawal. Medication fears and conflicting professional advice are recognized drivers of undertreatment (Steinberg 2015, PMID 25445824).

Exacerbation risk

A systematic review of 35 publications involving 429,583 pregnant women with asthma found higher attack risk with obesity, RR 1.25 (95% CI 1.15–1.37); smoking, RR 1.35 (1.04–1.75); depression/anxiety, RR 1.42 (1.27–1.59); and moderate-to-severe versus mild asthma, RR 3.44 (2.03–5.83) (Robijn 2022, PMID 35705210).

The same analysis reported associations with Black ethnicity, RR 1.62 (95% CI 1.52–1.73), and multiparity, RR 1.31 (1.01–1.68). Ethnicity should not be treated as biology: structural racism, care access, exposure and socioeconomic inequity are plausible upstream causes.

Modifiable risk Intervention
ICS reduction/nonadherence Explain benefit–risk; simplify and support access
Smoking/vaping Nonjudgmental cessation support and household protection
Obesity Appropriate nutrition/activity and obstetric monitoring; avoid blame
Poor technique Observe the actual device and use teach-back
Depression/anxiety Screen and connect to perinatal mental-health care
Rhinitis/reflux Treat clinically significant disease without misattributing asthma symptoms

Obesity is associated with worse asthma and pregnancy outcomes, but effect estimates are heterogeneous and intertwined with metabolic and social factors (Matsuzaki 2025, PMID 40500127). A treatable-traits model can expose these interacting risks without assuming one mechanism (Ramlal 2024, PMID 38471469).

Monitoring

Review every four to six weeks when feasible and sooner after deterioration. Assess symptoms, nocturnal waking, activity, reliever use, attacks, adherence and technique. Spirometry is safe when clinically indicated; do not accept declining airflow as a normal pregnancy change.

Peak flow can support a personalized action plan when the patient can measure reliably. Pulse oximetry is necessary in acute illness but is not a controller-monitoring substitute.

FeNO-guided management

FeNO can support type-2 assessment and ICS titration but is not a stand-alone disease or adherence test. Follow-up of the Managing Asthma in Pregnancy trial found doctor-diagnosed asthma in offspring at age 4–6 years in 25.9% after maternal FeNO-guided care versus 43.2% after symptom-guided care, OR 0.46 (95% CI 0.22–0.96). This was a secondary childhood follow-up of a single-center trial and needs replication (Morten 2018, PMID 29524536).

Medication principles

Class Pregnancy approach Main uncertainty/caution
ICS Continue effective therapy; cornerstone of prevention Use lowest dose maintaining control, not an ineffective dose
SABA Use for acute relief within an ICS-containing strategy Excess use signals poor control
ICS/LABA Continue when needed for control Product-specific data vary; avoid LABA without ICS
Leukotriene antagonist Continue selectively when clearly beneficial Smaller evidence base; neuropsychiatric discussion
LAMA Consider only when clinically indicated Less pregnancy-specific evidence
Systemic corticosteroid Use promptly for significant attack Maternal metabolic/vascular and fetal associations; confounding by severity
Biologic Individualized shared decision Sparse comparative and long-term infant data

Across observational experience, established inhaled asthma medications have not shown a risk signal that outweighs the danger of uncontrolled asthma; reviews consistently favor maintaining control (Rocklin 2011, PMID 21684328; George 2012, PMID 22383568).

The preference for a drug with more pregnancy exposure data is reasonable when efficacy is equivalent. It is not reasonable to destabilize a well-controlled patient solely to switch molecules without weighing the transition risk (Vieira 2022, PMID 33926358).

Inhaled corticosteroids

ICS treats the airway inflammation that drives attacks and systemic-steroid exposure. Dose reduction during pregnancy has been identified as a recurring precursor to exacerbation (Murphy 2025, PMID 41412710).

Local adverse effects are managed with technique, spacer where appropriate and mouth rinsing. Consider total steroid exposure, CYP3A4 interactions and signs of adrenal suppression at high doses, but routine undertreatment is not a safety strategy.

Montelukast

A 2024 meta-analysis did not find a statistically significant association with major congenital anomalies, RR 1.13 (95% CI 0.74–1.73), but reported associations with preterm delivery/low birthweight, OR 1.82 (1.35–2.45), and substantial uncertainty for spontaneous abortion. Residual confounding by asthma severity is likely (Fareed 2024, PMID 39129058).

Biologics

Pregnant people were generally excluded from pivotal biologic RCTs. A 2022 review found mostly case reports, case series and observational studies totaling 313 pregnancies; it found no clear adverse pattern but was far too small to exclude uncommon outcomes (Shakuntulla 2022, PMID 35987486).

EXPECT prospectively followed omalizumab-exposed pregnancies. Among 169 known outcomes there were 156 live births, one fetal death/stillbirth, 11 spontaneous abortions and one elective termination; 7/160 infants had a major defect and no anomaly pattern emerged. Lack of randomization and severe-asthma comparator complexity limit inference (Namazy 2015, PMID 25441639).

An international Delphi consensus supports individualized initiation or continuation of asthma biologics during conception, pregnancy and breastfeeding when otherwise indicated, while explicitly calling for registries; consensus is expert guidance, not proof of safety (Naftel 2025, PMID 39216499).

A live ClinicalTrials.gov re-query on 2026-08-30 identified more molecule-specific observation than an undated “sparse data” label implies: the dupilumab post-authorization pregnancy study is completed with 581 participants and includes asthma ([NCT04173442](https://clinicaltrials.gov/study/NCT04173442){target="_blank" rel="noopener"}); the omalizumab EXPECT registry completed with 309 participants ([NCT00373061](https://clinicaltrials.gov/study/NCT00373061){target="_blank" rel="noopener"}); and the benralizumab pregnancy-exposure study terminated after enrolling 299 ([NCT03794999](https://clinicaltrials.gov/study/NCT03794999){target="_blank" rel="noopener"}). These records positively define the gap: evidence is observational, uneven by molecule, and not a randomized comparison of maternal asthma control, fetal outcomes and long-term child outcomes.

For each decision document:

  1. prior attacks and systemic-steroid burden;
  2. response to the biologic and risk of withdrawal;
  3. available molecule-specific pregnancy data;
  4. gestational timing and placental-transfer considerations;
  5. patient values and alternative treatments;
  6. reporting to an appropriate pregnancy registry where available.

Treating an attack

An acute asthma attack in pregnancy is a maternal and fetal oxygenation emergency. Do not delay standard bronchodilator, oxygen, systemic corticosteroid or escalation solely because the patient is pregnant.

Priority Action
Severity Speech, work of breathing, mental state, respiratory rate, pulse, PEF/FEV1
Oxygenation Prompt supplemental oxygen for hypoxemia with pregnancy-appropriate target
Bronchodilation Repeated inhaled SABA; add ipratropium for severe attack
Inflammation Early systemic corticosteroid for moderate/severe or incomplete response
Escalation Magnesium and critical-care support when severe/refractory
Obstetric care Gestation-appropriate fetal assessment after maternal stabilization begins

A “normal” carbon dioxide in a distressed pregnant patient can signal fatigue because pregnancy normally lowers PaCO2. Silent chest, exhaustion, altered consciousness, cyanosis and worsening gas exchange demand immediate critical-care involvement.

After recovery, reconstruct why the attack occurred, restore controller therapy, observe technique, update the written plan and arrange rapid follow-up. Obstetric review should be based on gestation and event severity.

Labor, delivery and postpartum

Asthma alone rarely dictates delivery mode or timing. Continue usual inhaled treatment through labor. Ensure reliever availability and communicate chronic systemic-steroid exposure because stress-dose management may be needed in selected patients.

Postpartum, reassess control, sleep disruption, mood, smoking exposure, access and adherence. Most inhaled therapies are compatible with breastfeeding because systemic exposure is low, but confirm current product-specific lactation information, especially for biologics (PMID 36411004).

Avoid nonselective beta-blockers and bronchoconstricting prostaglandins when reasonable alternatives exist; obstetric indications and emergency context still require individualized risk assessment (Dombrowski 2004, PMID 14704237).

Reproductive health beyond pregnancy

Ask about pregnancy intentions when selecting long-term therapy, without assuming fertility goals. Contraception, assisted reproduction, miscarriage history, menstruation-related worsening and menopause can affect preferences and control. Evidence about sex hormones and asthma is biologically plausible but heterogeneous and does not support a single hormone-based asthma phenotype (Baldaçara 2017, PMID 28076614).

Preterm birth itself is associated with later childhood asthma, random-effects OR 1.37 (95% CI 1.30–1.43), creating a possible intergenerational pathway while not proving that maternal asthma is its sole cause (Jaakkola 2006, PMID 17030233).

Communication traps

Avoid Replace with
“No drug is safe in pregnancy” “Here is what is known, uncertain and the risk of not treating”
“Just stop if worried” “Contact us before changing controller treatment”
“Breathlessness is normal” “Some dyspnea is common; wheeze/airflow loss requires assessment”
“The biologic is safe” “Available data show no clear signal, but sample size is limited”
“Asthma caused this outcome” “Asthma is associated; disease, treatment and other factors interact”

Open questions

  • Which biologics have the best comparative pregnancy, lactation and long-term child safety? Molecule-specific observational studies exist, but no randomized comparative safety framework was identified in the 2026-08-30 registry/PubMed re-query (Naftel 2025, PMID 39216499; NCT04173442; NCT00373061; NCT03794999).
  • Does FeNO-guided pregnancy management reproducibly improve maternal attacks and childhood respiratory outcomes? (Morten 2018, PMID 29524536)
  • Which mechanisms connect maternal asthma activity to pre-eclampsia, growth and preterm birth?
  • How can medication-risk communication prevent ICS withdrawal without minimizing real uncertainty?
  • Which postpartum interventions prevent loss of control during sleep disruption and care transition?

References

  1. Murphy VE, Namazy JA, et al. Adverse perinatal outcomes in women with asthma: meta-analysis. BJOG. 2011. PMID 21749633
  2. Wang M, et al. Maternal asthma and hypertensive disorders of pregnancy: meta-analysis. Hypertens Pregnancy. 2020. PMID 31762345
  3. Robijn AL, et al. Risk factors for asthma exacerbations during pregnancy: systematic review and meta-analysis. Eur Respir Rev. 2022. PMID 35705210
  4. Colas K, Namazy J. Asthma in pregnancy: review of recent literature. Curr Allergy Asthma Rep. 2024. PMID 38477324
  5. Bravo-Solarte DC, et al. Asthma in pregnancy. Rev Alerg Mex. 2023. PMID 36719688
  6. Matsuzaki H, et al. Obesity and asthma during pregnancy: systematic review and meta-analysis. J Obstet Gynaecol Res. 2025. PMID 40500127
  7. Ramlal M, et al. Treatable traits in pregnant women with asthma. J Allergy Clin Immunol Pract. 2024. PMID 38471469
  8. Steinberg JA. Perception versus reality: controller medication and fetal risk. J Asthma. 2015. PMID 25445824
  9. Morten M, et al. Managing Asthma in Pregnancy trial: FeNO and childhood asthma. J Allergy Clin Immunol. 2018. PMID 29524536
  10. Rocklin RE. Asthma medications and maternal/fetal outcomes. Clin Mol Allergy. 2011. PMID 21684328
  11. George J, Abramson MJ, et al. Asthma in pregnancy: are inhaled corticosteroids safe? Am J Respir Med. 2012. PMID 22383568
  12. Vieira AC, et al. Asthma and pregnancy in the 2020 decade. Pulmonology. 2022. PMID 33926358
  13. Murphy VE. Decreasing ICS in pregnancy increases exacerbation risk. Respirology. 2025. PMID 41412710
  14. Fareed A, et al. Montelukast use in pregnancy: systematic review and meta-analysis. J Asthma. 2024. PMID 39129058
  15. Shakuntulla F, Chiarella SE. Safety of biologics for atopic diseases during pregnancy. J Allergy Clin Immunol Pract. 2022. PMID 35987486
  16. Namazy J, et al. Xolair Pregnancy Registry (EXPECT). J Allergy Clin Immunol. 2015. PMID 25441639
  17. Naftel J, et al. International consensus on asthma biologics in pregnancy. Lancet Respir Med. 2025. PMID 39216499
  18. L Ramos C, Namazy J. Monoclonal antibodies (biologics) for allergic rhinitis, asthma, and atopic dermatitis during pregnancy and lactation. Immunol Allergy Clin North Am. 2023. PMID 36411004
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  21. Lao TT, Hui SYA. Obstetric aspects of maternal asthma. Best Pract Res Clin Obstet Gynaecol. 2022. PMID 36210285
  22. Shaked E, et al. Maternal asthma: pregnancy course and outcome. J Matern Fetal Neonatal Med. 2019. PMID 28847192
  23. Murphy VE. Asthma in pregnancy: management, comorbidities and long-term health. Semin Respir Crit Care Med. 2022. PMID 35871149
  24. Popa M, Peltecu G, et al. Asthma in pregnancy: review and recommendations. Maedica. 2021. PMID 34221160
  25. Jaakkola JJ, et al. Preterm delivery and asthma: systematic review and meta-analysis. J Allergy Clin Immunol. 2006. PMID 17030233
  26. Davis AE, Wechsler ME. Safety of asthma treatment strategies in pregnancy. Curr Opin Pulm Med. 2025. PMID 40536883
  27. Baldaçara RP, Silva I. Association between asthma and female sex hormones. Sao Paulo Med J. 2017. PMID 28076614
  28. ClinicalTrials.gov API v2. Pregnancy-safety records re-fetched 2026-08-30. NCT04173442; NCT00373061; NCT03794999.