Center for Reproductive Medicine - H1N1 Influenza Virus and Pregnancy

H1N1 Influenza Virus and Pregnancy

What should I know about the H1N1 influenza virus?

The H1N1 virus is an influenza flu virus that has not been commonly seen as one of the seasonal influenza viruses that appear every year. Since fewer people have immunity to this virus, public health officials expect more people to be affected by flu symptoms than usual.

How does it affect pregnancy?

All influenza viruses can cause more problems in pregnant patients than in the general population. The H1N1 virus appears to be even more dangerous for some pregnant patients. They have a greater chance of developing serious pneumonia requiring admission to the hospital, and in rare cases, this pneumonia has resulted in death.

How likely am I to have a serious complication if I am pregnant and get the flu?

The Center for Disease Control (CDC) has offered some necessarily crude approximations. Preliminary findings show that pregnant women have represented 7% of the deaths reported to date from H1N1, or 7 times the expected number. This suggests that pregnant women are particularly vulnerable to this virus.

An estimate of the risk of dying from complications of the H1N1 virus if you are pregnant is 7/10,000 pregnant women.

To put this number in some perspective, the chance of death from pregnancy and delivery without the flu (the maternal mortality rate) is 1/10,000. Therefore, getting the flu when you’re pregnant gives you a 7/10,000 chance of dying. However, if you do get the flu when you’re pregnant, 9993/10,000 pregnancies will be just fine.

Is there anything more reassuring than that?

Yes. None of the deaths reported to date occurred in patients who had the vaccine. The vaccine appears to be 98% effective in stimulating antibodies to fight the infection. Even though the vaccine is not 100% effective in preventing you from getting the flu, it is reported to make the symptoms of the flu less severe.

In addition, there is a pill called Tamiflu which is active against the virus when taken within 48 hours of the onset of flu symptoms. This pill should significantly diminish the chance of serious lung infection from the virus.

Are the vaccine and the Tamiflu pill safe to take in pregnancy?

The overwhelming scientific consensus is that the influenza vaccines that have been given to pregnant women through the years are safe. The H1N1 vaccine is new this year for this particular virus, but experts feel there is no reason to think this vaccine should be any less safe than previous versions. The flu vaccine should be an individual dose, not taken from a multiple dose vial to avoid any concerns about the preservative agent thimerosal.

Tamiflu is a Category C drug, meaning there have been no studies in humans on its safety. However, it is felt to have a safety profile which makes it preferable to be treated if you have the flu, rather than “tough it out”, given the risks of this virus in pregnancy.

A word about “safe”

If by safe you mean have these two medications been tested in thousands of pregnant women and have their offspring been evaluated until they have reproduced healthy children, the answer is no. As you have all heard before, there is no drug or treatment in medicine that does not have a potential adverse effect. The assumption is that the adverse effect occurs infrequently enough and is not as serious as is the frequency and seriousness of the condition you’re trying to treat or avoid.

Absent observed and reported data, we are forced to rely on the educated opinions of experts. These experts have suggested that pregnancy is a particularly vulnerable time to have the flu for both you and your baby and recommend that each pregnant woman receive the H1N1 vaccination as well as the seasonal flu vaccination. They have also recommended treatment with Tamiflu if you are pregnant and experience flu symptoms.

CRM concurs with these recommendations, and will try to make it as easy as possible for our patients to follow them by making the H1N1 flu vaccine available in our clinic when it becomes available through the Minnesota Health Department.

Because of logistical problems, we will not have the seasonal flu vaccine available to our patients in clinic. Therefore our patients are advised to have this vaccine administered through their primary clinic or neighborhood locations where this vaccine is routinely offered.

What do I do if I get the flu?

If you are pregnant Public Health Authorities recommend that you be treated with Tamiflu, which we will call in to your pharmacy. Tamiflu works best if started within 48 hours of the onset of flu symptoms. There is no clinically useful test to determine if your flu symptoms are definitely from H1N1, so during this pandemic, recommendations are that you assume you have the H1N1 virus and start treatment with Tamiflu.

In addition to Tamiflu, take Tylenol to keep your fever as low as possible.

Report to a medical facility with the ability to admit you if you are having difficulty breathing.

What do I do if I’m pregnant and my child or partner gets the flu?

Recommendations differ here. Some would say to take a lower dose of Tamiflu to lower your chance of getting the flu. Others would say wait to see if you develop flu symptoms, then start Tamiflu. If you have any other risk factors such as Asthma or immune deficiencies you should contact your physician who treats you for these conditions and get advice.