Volume 17, No. 4, Fall 2009
By Jean Talbert, M.D.
The H1N1 influenza virus has spread rapidly throughout the world since it was first identified in spring 2009 in Mexico. Hundreds of thousands of cases have already been confirmed and there have been over 4,000 deaths. These are surely underestimates as many probable flu cases have not been confirmed.
Pregnant women have been identified as one of the highest risk groups to develop severe infections. They are four times as likely to be hospitalized and more likely to have serious complications. They represent 6 percent of the flu deaths worldwide, but make up only 1 percent of the general population.
Why are pregnant women so severely affected?
Part of the risk is due to the normal physiologic changes during pregnancy. Pregnant women, especially in the third trimester, have decreased functional lung capacity and therefore less reserve when a pneumonia occurs; they have a less effective bodily immune response and a higher risk of blood clots. Bed-rest, if required, can lead to deep vein clots and life-threatening pulmonary emboli.
Good general health is helpful, but does not alter these normal physiologic facts.
Fortunately, no cases of transmission of the virus across the placenta have been identified although the fetus can be affected indirectly from higher risks of preterm labor and preterm rupture of membranes. High fevers and low oxygen state also can cause fetal distress.
Pregnant women with flu symptoms or following direct contact with someone diagnosed with the flu should contact their physicians immediately. Most anti-viral medications are safe and should be prescribed within two days of the onset of symptoms. Prophylactic anti-virals are recommended for pregnant women after known exposures.
A better course is to prevent the infection altogether. Avoiding individuals with flu-like symptoms, frequent hand washing with soap and water or alcohol-based sanitizers and frequent cleaning of handles, telephones and faucets with antiseptics is essential. If diagnosed with the flu, limit contact with others for at least seven days after onset of symptoms or until symptoms have been gone for at least 24 hours.
Pregnant women are strongly encouraged to obtain both the seasonal flu and the H1N1 flu shot. Both are FDA approved and CDC recommended for pregnant women. They’re made using similar laboratory processes so there is little reason to believe that the H1N1 vaccination is less safe. No unusual ill effects have been identified in clinical trials.
Neither flu shot is made of live virus so there is essentially no risk of contracting the flu from the shot. They can be safely given at the same time although in different arms. There is no strong evidence that the vaccine preservative thimerosal is harmful, but manufacturers are making preservative-free vaccines available for pregnant women and young children.
Getting a flu shot during pregnancy transmits antibodies to the fetus so, after birth, they help to protect infants too young to be vaccinated themselves. Breastfeeding after vaccination also may provide some added protection.
Women with the flu infection should avoid close contact with their babies, but breast milk can be pumped and fed to the infant. Antiviral medications are believed safe while breastfeeding.
Don’t take the vaccines if you have severe egg allergies, a severe reaction to a previous flu shot or the rare neurological disorder, Guillain-Barre.
All pregnant women and caregivers of infants and small children should obtain these vaccines. The more people who are vaccinated, the better our chances of protecting ourselves, our families and our communities from this potentially dangerous pandemic.
(Dr. Talbert is a board certified OB/GYN specialist practicing with Cape Obstetrics, Midwifery & Gynecology in Falmouth and Sandwich, 508-457-0088.)