Influenza in Pregnancy

Comment from expert advisory group

Influenza-like illness (ILI) is defined as sudden onset of symptoms with at least one of these three respiratory symptoms: cough; sore throat; shortness of breath in addition to at least one of the following four systemic symptoms: fever/feverishness; malaise; headache; myalgia.
Pregnant women are at increased risk of severe influenza compared to non-pregnant women of reproductive age.
The risk of complications from influenza is higher in the second and third trimesters of pregnancy and is greater for pregnant women with at-risk medical conditions.
Postpartum women are also at increased risk of severe influenza up to two weeks postpartum (including following pregnancy loss).
The diagnosis of influenza should be considered in all patients presenting with acute respiratory infections (ARI) regardless of their vaccine status.
During the influenza season, treatment of suspected severe influenza should not be delayed while awaiting laboratory test results. Empiric antiviral treatment should be started as soon as possible, ideally within 48 hours of symptom onset.
Antiviral treatment is recommended for pregnant women or women up to two weeks postpartum (including following pregnancy loss) with suspected or confirmed severe influenza, and can be taken during any trimester of pregnancy.
The patient should be referred to hospital for assessment if there is any respiratory compromise or suspicion of a bacterial super-infection.
For post-exposure chemoprophylaxis, refer to the chemoprophylaxis section of this guidance below.
Pregnant women should be advised of the signs and symptoms of ILI/ ARI and encouraged to present early to their GP, local acute hospital or maternity unit if they develop ILI/ARI symptoms or any respiratory symptoms after close contact with a person who has ILI/ARI or laboratory confirmed influenza.
The most effective way to minimise the risks of influenza infection and associated complications during pregnancy is through vaccination. Influenza vaccination should be recommended and offered to all women pregnant at any time from October to April. The vaccine can be given at any stage of pregnancy. Encourage patients to receive the vaccine as early in pregnancy as they can. For more information on influenza vaccination please visit the HSE website on flu and flu vaccines.
The HPSC provides full guidance on the management of pregnant and postpartum women with suspected influenza.
For guidance on influenza treatment for non-pregnant women, please visit our seasonal influenza page.

Treatment

Influenza in Pregnancy Treatment Table
Drug	Dose	Duration	Notes
1st choice options
Oseltamivir	75 mg every 12 hours	5 days	Can be taken during any trimester of pregnancy. Dose reduction required in renal impairment (eGFR <60 mL/min/1.73 m² or CrCl ,60 mL/min) If patient weighs 40kg or less, consider a lower dose of 60mg every 12 hours(i.e.>23-40 kg dose for those aged >1-12 years)

Chemoprophylaxis

Post-exposure antiviral chemoprophylaxis can be considered for certain pregnant women and women who are up to two weeks postpartum (including following pregnancy loss) who have had close contact with someone likely to have been infectious with influenza and who:
- cannot receive an influenza vaccination due to a contraindication or because vaccine is not available, or
- have severe immune deficiencies or other medical conditions that make them unlikely to respond to influenza vaccination
Clinical judgement should be exercised in individual cases to determine if the benefit of receiving chemoprophylaxis outweighs the risk.
Previous influenza vaccination does not preclude the use of post exposure prophylaxis.

Influenza in Pregnancy Post-Exposure Chemoprophylaxis Treatment Table
Drug	Dose	Duration	Notes
1st choice options
Oseltamivir	75 mg every 24 hours	10 days	Can be taken during any trimester of pregnancy. Dose reduction required in renal impairment (eGFR <60 mL/min/1.73 m² or CrCl ,60 mL/min) If patient weighs 40kg or less, consider a lower dose of 60mg every 24 hours(i.e.>23-40 kg dose for those aged >1-12 years)

Patient Information

HSE A-Z, Pregnancy and flu vaccine
HSE A-Z, Flu - symptoms, diagnosis and treatment
An information sheet on ‘Antibiotics and breastfeeding' is available from the Breastfeeding Network UK
Further information on Antibiotics and Breast-feeding can be found on the Mother to Baby website (USA) (Search or Use Browse by Medications category).
HSE My Child is a useful resource for breastfeeding support and general guidance.

Safe Prescribing (visit the safe prescribing page)

Doses are oral and for adults unless otherwise stated
Dosing in children quick reference dosage/weight guide
Renal impairment dosing table
Safety in Pregnancy and Lactation
Drug interactions table. Extensive drug interactions for clarithromycin, fluoroquinolones, azole antifungals and rifampicin. Many antibiotics increase the risk of bleeding with anticoagulants.
Visit the Health Products Regulatory Authority (HPRA) website for detailed drug information (summary of product characteristics and patient information leaflets). Dosing details, contraindications and drug interactions can also be found in the Irish Medicines Formulary (IMF) or other reference sources such as British National Formulary (BNF) / BNF for children (BNFC).

Reviewed January 2025