Effect Measure

Flu can be a nasty illness, nasty enough to kill you. Pregnant women are at more risk than others because their physiology is altered. They are carrying a foreign body (the fetus) so their immune response is not the same, and their cardiovascular and respiratory physiology are also different. CDC is reporting about 20 swine flu cases in pregnant women, and late yesterday they gave a more detailed description of three cases, one of which ended fatally:

Patient A. On April 15, a woman aged 33 years at 35 weeks’ gestation with a 1-day history of myalgias, dry cough, and low-grade fever was examined by her obstetrician-gynecologist. She had been in relatively good health and had been taking no medications other than prenatal vitamins, although she had a history of psoriasis and mild asthma. The patient had not recently traveled to Mexico. Rapid influenza diagnostic testing performed in the physician’s office was positive.

On April 19, she was examined in a local emergency department, with worsening shortness of breath, fever, and productive cough. She experienced severe respiratory distress, with an oxygen saturation of approximately 80% on room air and a respiratory rate of approximately 30 breaths per minute. A chest radiograph revealed bilateral nodular infiltrates. The patient required intubation and was placed on mechanical ventilation. On April 19, an emergency cesarean delivery was performed, resulting in a female infant with Apgar scores of 4 at 1 minute after birth and of 6 at 5 minutes after birth; the infant is healthy and has been discharged home. On April 21, the patient developed acute respiratory distress syndrome (ARDS). The patient began receiving oseltamivir on April 28. She also received broad-spectrum antibiotics and remained on mechanical ventilation. The patient died on May 4.


Patient C. On April 29, a woman aged 29 years at 23 weeks’ gestation was experiencing cough, sore throat, chills, subjective fever, and weakness of 1 day’s duration and was seen at the family practice clinic where she had been receiving prenatal care. The patient had a history of asthma but was not taking any asthma medications. Her son, aged 10 years, reportedly had similar symptoms the week before the onset of her symptoms. Another son, aged 7 years, had become ill on the same day as his mother and accompanied her to the clinic. At the clinic, the younger son was coughing vigorously and was asked to put on a mask by office staff members. Rapid influenza diagnostic testing in the family practice clinic of a nasopharyngeal sample from patient C was positive. The woman was prescribed oseltamivir, which she began taking later the same day. Her symptoms are resolving without complications, and her pregnancy is proceeding normally. (CDC, Morbidity and Mortality Weekly Report [MMWR])

Patient C’s obstetrician was also pregant (13 weeks) and she was started on oseltamivir immediately. So far the swine flu virus is sensitive to the neuriminidase inhibitor antivirals, oseltamivir (Tamiflu) and zanamivir (Relenza), but oseltamivir is recommended for pregnant women because it is absorbed systemically. The oseltamivir tablet is not the active form of the drug but a “pro-drug” designed to be absorbed in the gastrointestinal tract. Once in the blood it is converted to the active form by enzymes in the liver. Zanamivir is already in the active form but cannot be absorbed. It is administered with an inhaler, so only affects virus in the respiratory tract. CDC believes it is preferable to get the drug to other organs, including the placenta.

Do we know that oseltamivir is safe for the fetus? No good safety studies have been done, but what evidence exists does not suggest risk to the fetus. Given the risk of influenza, CDC believes the risk-benefit balance nets out in favor of 5 days of oseltamivir use in pregnant women as early in their illness as possible.


  1. #1 Noadi
    May 13, 2009

    This hits a bit too close to home. My sister in law is stationed at a base in Texas and is pregnant with her and my brother’s first child. This is the type of thing I worry about, more so than my own health.

  2. #2 Phila
    May 13, 2009

    Given the risk of influenza, CDC believes the risk-benefit balance nets out in favor of 5 days of oseltamivir use in pregnant women as early in their illness as possible.

    It shocks me that they didn’t start Patient A on oseltamivir on the 19th, when she turned up in the ER…especially since she’d already been diagnosed with flu. But I do understand how difficult it must be to make decisions like these, and how easy it is for a non-expert to say what should’ve been done in hindsight.

    But do you have any idea why they’d wait an additional week after she developed ARDS? That seems completely bizarre to me, especially since the baby had already been delivered. What would be the medical rationale for something like that?

    A really sad story, in any case.

  3. #3 Yasser Fathi, MD
    September 21, 2009

    I do agree with the comment by Phila. I’m intensivist and I had the chance to manage a 27 weeks pregnant woman who catched infection from her brother who was treated short time before. She was put on mechanical ventilator, developed ARDS. We started oseltamivir 150 mg BID and low dose methylprednisolon infusion. Due to premature rupture of membranes, she had C.S. The baby (1.7 kg) was put on M.V. for 2 days, recieved surfactant and successfully weaned. The bilateral lung infiltrates dramatically improved after C.S. We hardly but successfully weaned her after 2 weaks of M.V. and she is still on respiratory and rehabilitation training.

  4. #4 MarShep
    January 17, 2012

    I contracted influenza A in January 2011 while 19 weeks pregnant. I was already a high risk pregnancy due to age and previous premature deliveries.
    I was admitted immediately after they took my vitals at the ov clinic at IU hospital and spent the next 8 days in OB/ICU. it was the first year I had missed my flu shot in many years even though I had mentioned getting one to both my OB and family doctors.
    They tried to get me to get a CT scan with contracts to check for pulmonary embolisms but I refused due to the risk of contrast to my unborn child.
    I was also asked if I wanted to terminate my pregnancy.
    I spent the rest of my pregnancy plus some on at home oxygen.
    My daughter was born 5 weeks premature, small but otherwise seemingly healthy. She had/ has some mild nerve issues that are slowly improving. Twitching, shaking of random limbs, head. Slow physical development as far as rolling over, sitting, etc. about 2 months behind others her age.
    I am now a flu shot advocate. I tell everyone. Especially those that are pregnant, close to pregnant women or newborns/infants.
    now that I’ve experiences how dangerous that influenza A is I do what I can to prevent it. I felt horrible pretty much the rest of my pregnancy. I tired much easier, shortof breath, beside the fact of worrying how the flu and medications, X-rays and low oxygen stats effected my daughter.
    Get vaccinated!!!!!!