Hay fever in pregnancy

Rhinitis affects at least 20% of pregnancies and can start during any gestational week. Although the pathogenesis is multifactorial, nasal vascular engorgement and placental growth hormone are likely to be involved (1):

• pregnancy rhinitis has been defined as nasal symptoms during pregnancy lasting six or more weeks without other signs of respiratory tract infection and with no known allergic cause, disappearing completely within two weeks after delivery
  • patients complain of persistent nasal congestion, accompanied by watery or viscous clear nasal secretions
  • nasal congestion can lead to mouth breathing at night and reduced quality of sleep

Pre-existing rhinitis may worsen, improve, or remain unchanged during pregnancy:

• allergic rhinitis is usually pre-existing, although it may develop or be recognised for the first time during pregnancy

Management of hay fever during pregnancy can include:

• allergen avoidance
  
  
• pharmacological treatment
  • drug therapy of allergic rhinitis in pregnancy is indicated if symptoms are persistent
    • topical administration should be considered first-line since there is minimal systemic absorption (1)
  • risk of drug-induced malformations is highest during the first trimester - therefore, if possible, drug treatment should be avoided during this period
  • if allergen avoidance is ineffective and/or the patient is unable to tolerate their symptoms, then
    • topical treatment with intranasal beclometasone and/or sodium cromoglicate (intranasal or intraocular) should be considered first line, as topical administration minimises systemic absorption (1,2,3)
      
      
      • topical treatment with ocular mast cell stabilisers (for example, sodium cromoglicate) or intranasal corticosteroids (for example, fluticasone) can be considered if non-pharmacological management is insufficient.
        • topical treatments act locally and have lower systemic absorption (and fetal exposure) than oral preparations
        • intranasal corticosteroids are also the most effective treatment for allergic rhinitis (1)
      • there is limited data on intranasal corticosteroid use during pregnancy limited; however the data for systemic corticosteroids used in pregnant women for other indications (e.g. asthma) suggest that risks are small
      • oral corticosteroids have not been associated with an increased rate of malformations (2)
        • however, high doses (over 50mg daily of oral prednisolone) if used over long periods have been associated with fetal growth retardation in a small number of patients (2)
          
          
    • use of oral decongestants during pregnancy
      • this is not generally recommended because of conflicting data, the risk of rebound congestion and a possible association with fetal toxicity
        • there are a small number of case reports, which imply that pseudoephedrine may be associated with an increased risk of gastroschisis (congenital fissure of the abdominal wall). Note though that two observational studies involving women who had been exposed to pseudoephedrine found no increased adverse outcomes compared with controls (2)
        • s a theoretical risk of vasoconstriction affecting placental and foetal perfusion and therefore should be avoided in the first trimester and in women with hypertension. Other reported malformations include limb reduction defects
        • is not known whether the oral or intranasal decongestant preparations cross the placenta - it is suggested though that most expert advice concludes that all decongestants be avoided in pregnancy (2)
          
          
    • topical antihistamine - preferred over oral antihistamines due to rapid onset of action and minimal systemic absorption
      
      
    • if an oral antihistamine is required then consult BNF for guidance - oral antihistamines are a second line treatment (1,2)
      • non-sedating antihistamines are preferred because of the risks associated with drowsiness in the mother
      • loratadine and cetirizine are the preferred antihistamines for pregnant women (1)
      • chlorphenamine can be used if a sedating antihistamine is needed
        
        
• montelukast
  • due to a lack of information, montelukast should not be used solely to treat allergic rhinitis, but may be used to treat concomitant asthma (1)
    
    
• immunotherapy - however this is only after consultation of expert advice
  • allergen-specific immunotherapy can be continued carefully during pregnancy in patients who are already deriving benefit from it
  • note though that the risk of anaphylaxis is higher in pregnant women - therefore immunotherapy should not be started nor doses increased, unless there is a serious clinical need

Notes:

• use of sodium cromoglicate, topical corticosteroids, loratadine, cetirizine, chlorphenamine or fexofenadine during pregnancy is not usually regarded as grounds for additional fetal monitoring (1)

Reference:

1. NHS Specialist Pharmacy Service (January 2025).Hay fever or allergic rhinitis: treatment during pregnancy
2. MeReC bulletin (2004); 14(5):17-20.
3. Clinical knowledge summaries, safe practical clinical answers. Allergic rhinitis