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)
      
      
      • 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)
      • most pregnant women who require oral antihistamines are most appropriately treated with a second-generation agent (cetirizine, levocetirizine, or loratadine) because these drugs are less sedating and have fewer cholinergic side effects compared with first-generation agents such as chlorphenamine (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:

• decongestants and leukotriene receptor antagonists should be avoided, though the latter can continue for allergic rhinitis in pregnancy if already being used for asthma during pregnancy (1)
• options such as intranasal azelastine, intranasal ipratropium bromide, montelukast, oral corticosteroids, and decongestants should have their risk:benefit assessed on a case-by-case basis given the lack of published safety data relating to their use in allergic rhinitis during pregnancy (1)

Reference:

1. NHS Specialist Pharmacy Service (July 2020). Which medicines can be used to treat allergic rhinitis during pregnancy?
2. MeReC bulletin (2004); 14(5):17-20.
3. Clinical knowledge summaries, safe practical clinical answers. Allergic rhinitis