What is the flu?
Flu or influenza is a contagious viral infection caused by certain RNA viruses belonging to the Orthomyxoviridae family (influenzavirus A, B and C). Flu during pregnancy can be harmful for the fetus, especially in the later stages, unless treated properly .
Causes of flu during pregnancy
Pregnancy alters your hormone levels and immune system functioning, so your body does not refuse the changes occurring in your body. Otherwise, your immune system would try to get rid of the fetus, which is a foreign element to your body . On the other hand, you become much more susceptible to infections and diseases as your immune system is no longer able to fight them off as well as before you got pregnant . Due to this reason, you are more likely to get affected by flu while pregnant.
What are the signs and symptoms of flu (influenza) during pregnancy?
The influenza virus has an incubation period of 3-5 days, meaning the virus takes 3-5 days to multiply in your body and cause visible symptoms .
- Headache 
- Fatigue and tiredness 
- Loss of appetite
- Body and muscle pain
- Sore throat 
- Stuffy or runny nose
What are the risks of influenza while pregnant?
The mother may develop life threatening complications such as:
- Premature labor
- Preterm delivery 
- Bronchial infections 
- Encephalitis (inflammation of brain tissues)
- Otitis media (a type of middle ear infection) 
- Septic shock (life threatening blood infection that leads to lowering of blood pressure)
- Meningitis (infection of the central nervous system)
Risks to the baby mainly include those associated with preterm delivery, such as low birth weight. Other potential risks include stillbirth and death of the baby within a week after birth , while recent studies show that flu in the mother also increases the chances of the baby developing conditions like autism  and bipolar disorder .
How to prevent the flu while pregnant?
- Following a diet containing fresh vegetables, fruits and wholegrain rich in antioxidant vitamins and minerals to help your body fight infections 
- Avoiding sharing foods and utensils with others
- Avoiding touching your nose, eyes and throat as much as possible 
- Following a light exercise schedule to improve circulation and fight infections
- Avoiding direct contact with people suffering from cold
- Carrying a hand sanitizer at all times and using it whenever necessary
- Giving up smoking as, in addition to harming the fetus, tobacco also causes further damage to your immune system 
Is it safe to get a flu shot while pregnant?
Getting the vaccination before the influenza season (early October to May)  is the only way of preventing the disease in pregnant women . According to the NHS, the flu shot is safe for all women, whether in their first, second or third trimesters . It can be given along with the vaccine for whopping cough without any adverse reactions . It is recommended to talk to your doctor regarding the flu jab and its potential effects.
Can you get the flu from the flu vaccine?
This is one of the most common myths about the flu immunization process. However, there is no risk of getting sick from the vaccine as it only contains dead viruses as its principal ingredient . The nasal spray shot known as live, attenuated influenza vaccine (LAIV) contains weakened (attenuated)  viruses; but, it is strictly not recommended for pregnant women .
Flu shot side effects in pregnancy
Most women do not experience any adverse reactions while some may experience the following mild flu-like symptoms within a couple of days after getting the vaccine:
- Mild fever
- Headache 
- Runny nose
- Muscle aches
- Sore throat 
Some women may experience faintness and certain allergic reactions. However, the potential benefits of getting the flu vaccine surpass the possibility of adverse effects. People allergic to chicken eggs should avoid the regular vaccine as eggs are used for growing the inactivated viruses present in it . If you have an allergy, consult your doctor about getting the egg-free vaccine .
How much does the flu shot cost?
The cost for a single shot ranges between $5 and $10 .
Flu treatment during pregnancy
The condition is usually diagnosed based on the symptoms. But in some cases, your doctor may run a few influenza tests to confirm the diagnosis. It is crucial to start the treatment at an early stage of the infection to avoid hospitalization and the use of potentially harmful antiviral drugs.
Home remedies for flu
- Bed rest
- Use a hot water bag or a wheat heat-pack  to relief muscle pain (hot water bottles during pregnancy)
- Use homemade saline nasal sprays can help reduce nasal congestion by loosening the mucus
- Add some lemon or honey to a cup of warm water and drinking it slowly to treat sore throat 
- Take a glass of warm water, add a teaspoon of salt to it and gargle to treat sore throat
- Fresh garlic is considered an effective natural remedy (as it is known to contain certain virus-fighting compounds) 
How to treat influenza with medicines?
Consult your doctor about taking over-the-counter medications like paracetamol (Tylenol) as they are generally considered safe for pregnant women . He or she can also prescribe some other safe antiviral medicine if necessary. It is vital to lower your temperature to prevent immediate complications. However, non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen are not considered safe during this time .
Tips for managing the symptoms
- Drinking lots of fluids (e.g. water and fresh fruit juices) to avoid dehydration and flush out any toxins from your system
- Eating small frequent nutritious meals to keep the energy levels up 
- Keeping your head propped up with a pillow when you lie down to manage the headache 
- Using humidifiers to keep the air moist
- Taking warm showers (hot baths during pregnancy)
How long does the flu last in pregnancy?
Usually, the symptoms of influenza remain for a few days to a week . However, according to some studies viral diseases like colds and flu tend to last 2-3 times longer in pregnancy .
How Long is the Flu Contagious?
You are likely to remain contagious as long as the symptoms persist . Some women may continue to shed the virus even after the treatment due to the weakened immune system.
When to call the doctor?
Call your doctor immediately in case of any of the following symptoms, even if you are on flu medication:
- Shortness of breath or any difficulty in breathing 
- Chest or abdominal pressure or pain
- High fever that refuses to go away
- Sudden dizziness
- Severe vomiting multiple times a day
- Confusion 
- Reduced or no baby movement 
- Persistent symptoms that refuse to improve even after 3-4 days 
- Severe coughing along with thick green-yellow mucus
- Symptoms that come back worse (with fever and coughing) after getting a little better with medicines 
Influenza ICD-9 and ICD-10 Codes
The ICD-9 code used for indicating flu is 487 , while its ICD-10 codes are J10 and J11 .[ref]
- http://apps.who.int/classifications/icd10/browse/2010/en#/J11 [/ref]