How Reemerging Influenza Affects Pregnancy & Childbirth

Every winter, the headlines warn us about a new wave of flu. This year, doctors worldwide are reporting a **reemergence** of more aggressive influenza strains, and the news hits hardest where it matters most: expecting mothers. If you’re pregnant or caring for someone who is, you’ll want to know exactly how this virus can change a pregnancy, what risks it brings to labour, and what you can do right now to stay safe.

Influenza is a contagious respiratory illness caused by influenza viruses that mutate regularly, leading to seasonal outbreaks and occasional pandemic spikes. The virus spreads through droplets when an infected person coughs, sneezes, or talks, and it can survive on surfaces for up to 24 hours. While most healthy adults recover within a week, the disease can become severe for high‑risk groups, including pregnant people.

Why Pregnancy Increases Flu Risks

Pregnancy isn’t just a nine‑month state of mind; it’s a complex physiological shift that reshapes the immune system, heart, and lungs. Two key changes make flu more dangerous:

• Maternal immune system undergoes a natural suppression to protect the fetus from being rejected. This immunomodulation means the body’s first line of defence against viruses is weaker.
• Cardiovascular output rises by up to 50% and the diaphragm is pushed up as the uterus expands, reducing lung capacity. The combination makes it harder to clear infections quickly.

These changes translate into a higher chance of developing complications such as pneumonia, dehydration, and even intensive‑care admission. A 2023 Australian cohort study found that pregnant women with flu were three times more likely to be hospitalized than non‑pregnant women of the same age.

Potential Effects on Pregnancy and Fetal Development

When Fetal development is exposed to high fever or severe maternal illness, several outcomes can occur:

• First‑trimester infections have been linked to a modest increase in miscarriage risk (about 1.5% higher in flu‑positive cases).
• Second‑ and third‑trimester infections raise the odds of preterm birth by 20‑30%.
• Neonatal influenza can lead to low birth weight, respiratory distress, and, in rare cases, stillbirth.

These statistics come from a systematic review that pooled data from 12 countries, including the UK, US, and Australia, covering over 150,000 pregnancies.

Impact on Labour and Delivery

Flu during the late stages of pregnancy can throw a wrench into labour plans. Here’s what clinicians see most often:

1. Fever may trigger uterine contractions, leading to spontaneous preterm labour.
2. Severe respiratory distress can make epidural placement riskier, sometimes prompting a move to general anaesthesia.
3. If the mother tests positive close to delivery, hospitals may isolate the newborn for the first 24‑48hours, impacting early skin‑to‑skin contact and breastfeeding initiation.

While most babies born to mothers with flu are healthy, the added stress on both mother and baby can increase the likelihood of a Caesarean section, especially if maternal oxygen levels drop.

Prevention: Vaccination Is the Cornerstone

Vaccines remain the most effective shield against flu‑related pregnancy complications. The World Health Organization (WHO) recommends that all pregnant people receive an inactivated flu vaccine at any stage of pregnancy, ideally before the flu season peaks.

Vaccine refers to a biological preparation that stimulates the immune system to recognize and fight specific pathogens without causing disease. In Australia, the Australian Immunisation Handbook (AIH) classifies the standard quadrivalent inactivated influenza vaccine (IIV) as “safe for all trimesters.”

Beyond vaccination, regular hand‑washing, avoiding close contact with sick individuals, and using masks in crowded indoor settings further cut transmission risk.

Treatment Options Safe for Mother and Baby

If you do catch flu, early antiviral therapy can lessen severity. The two antivirals most studied in pregnancy are oseltamivir (Tamiflu) and zanamivir (Relenza). Both are classified as Category C by the Therapeutic Goods Administration (TGA), meaning animal studies have shown some risk but benefits can outweigh potential harms when treatment is needed.

Guidelines from the World Health Organization advise starting antivirals within 48hours of symptom onset, especially for pregnant patients with fever, cough, or shortness of breath.

• Standard adult dose of oseltamivir: 75mg twice daily for five days.
• Zanamivir is inhaled; it’s an option for those who can’t tolerate oral meds, though data in pregnancy are limited.

Supportive care-hydration, rest, acetaminophen for fever-remains essential. Aspirin and ibuprofen are avoided because of potential fetal risks.

What to Do If You Feel Unwell

Recognizing flu early can save you and your baby from serious complications. Watch for these signs:

• Sudden fever >38°C (100.4°F) with chills.
• Dry cough, sore throat, or muscle aches that worsen after 24hours.
• Difficulty breathing, chest pain, or rapid heartbeat.

If any of these appear, call your obstetrician or local maternity helpline immediately. Ask for a rapid influenza diagnostic test (RIDT) and discuss starting antivirals. Most Australian hospitals have dedicated “flu clinics” for pregnant patients during peak season.

Australian Context: Local Resources & Statistics

In 2024, the Australian Department of Health reported a 15% rise in flu‑related hospital admissions among pregnant women compared with the previous year, coinciding with the spread of a H3N2 variant.

The Australian Immunisation Handbook recommends that every pregnant person receive the flu vaccine during routine antenatal visits, and it provides free vaccines through most Medicare‑eligible clinics.

Key local resources:

• FluWatch (government portal) - real‑time outbreak maps.
• National Perinatal Epidemiology and Statistics Unit - data on flu outcomes.
• Maternal and Child Health Hotline - 24/7 advice from specialised nurses.

Quick Checklist for Expecting Mothers

• Get the inactivated flu vaccine as early as possible this season.
• Keep a thermometer handy; check temperature twice daily if you feel unwell.
• Start antivirals within 48hours of symptoms-talk to your GP right away.
• Stay hydrated, rest, and avoid non‑steroidal anti‑inflammatory drugs.
• Practice strict hand hygiene and wear a mask in crowded indoor spaces.
• Know the nearest maternity hospital’s flu clinic and its opening hours.