by Mary Carmichael
Pregnant women already visit doctors far more frequently than most people do, and this winter, as swine flu spreads, a lot of scared women are going to be asking for extra appointments. It's not just moms-to-be being overly cautious: swine flu, or H1N1, can be more dangerous for pregnant women. If you’re expecting, here’s what you need to know about staying flu-free this winter.
Am I more likely to catch swine flu because I’m pregnant?
Probably. The immune system is slightly depressed during pregnancy, which leaves expectant mothers more vulnerable to infection by several pathogens, including but not limited to H1N1. (Others run the gamut from malaria to measles, from leprosy to several types of food poisoning.) Researchers are starting to figure out why this is the case, but “many unanswered questions remain,” according to the Centers for Disease Control.
Two weeks ago, a study of 16 pregnant women found that half of them had “mildly deficient” levels of a protective antibody called IgG2─and the lowest levels were in women who got seriously ill with the swine flu. Other, nonpregnant patients with bad cases of swine flu had low IgG2 levels, too, suggesting that the deficiency is an underlying weakness that isn’t limited to pregnant women. It’s possible that a pregnant woman with naturally high levels might be at less risk than another pregnant woman with naturally low levels. But of course, she wouldn’t know what her levels were─doctors aren’t likely to start testing for them based on such a small study. And of course, there are many other factors that can determine your individual risk.
Aside from molecular biology, there are more obvious reasons the immune system may be hampered during pregnancy, such as the fact that heavily pregnant women often find it difficult to sleep. A well-rested body is better able to fight off infection, with H1N1 or anything else. So getting extra rest, if possible, will be especially important this winter.
If I do catch swine flu, what are the chances that I’ll have a very severe case?
They’re higher than most people’s: since your immune system is weaker than usual, it won’t put up as much of a fight. Also, late in pregnancy, the baby pushes up against the diaphragm, making it harder to take deep breaths; that can be a serious problem if the flu turns into pneumonia.
Early in the epidemic, the CDC reported that pregnant women were hospitalized with swine flu four times as often as the general population. That number is still holding up as the epidemic grows, but it may change—epidemiologists aren’t quite sure how the disease will spread and mutate over the course of the winter.
Some news reports have also trumpeted a terrifying statistic from a CDC survey in which more than 13 percent of people who died of swine flu were pregnant women. (Pregnant women make up only 1 percent of the population). That statistic is misleading and unreliable. The survey looked at just 45 deaths, a sample far too small to yield much useful information. Newer, more reliable numbers are closer to 6 percent─still frightening, but less than half the original estimate. The CDC will keep refining that number throughout the flu season.
Will I be able to get vaccinated quickly against the swine flu?
Yes, but you may not be in the very first round of vaccinations. That’s because the first 6 million to 7 million doses are scheduled to ship in early October, and most of them are the nasal-spray version. Unlike the shot, the nasal spray contains live virus; doctors don’t want to take any chance of infecting pregnant women with the same disease they’re trying to ward off. (The nasal-spray vaccine against the regular flu is also inappropriate for pregnant women). The CDC has said that some flu shots may be available by early October as well, but it’s unclear how many.
By mid-October, there should be plenty of vaccine available for pregnant women─about 40 million doses will be ready by then.
Is getting a vaccine risky?
It’s certainly not as risky as skipping one. Many pregnant women are wary of taking any medications, and as a result less than than 25 percent get a regular flu shot. Some of them are clearly worried about the safety of the swine-flu shot, and doctors are worried that they’ll shun it. But there’s no apparent reason for them to do so. Testing of the swine-flu shot in the general public hasn’t shown any red flags about its use; the only side effects seem to be a bit of soreness at the vaccination site and possibly one day of feeling a little lousy. Trials focusing specifically on pregnant women are now underway.
Are there risks for the baby?
It appears there aren’t any risks of vaccination at all. (The ongoing trials in pregnant women will likely shed more light on this, but scientists aren’t expecting to find anything.) On the other hand, there are known risks for the baby if a mother gets the flu, swine or otherwise: the disease can trigger premature labor, and a high fever in the mother during the first trimester is also linked to neural-tube defects in babies.
Vaccination has a demonstrable benefit for a fetus: the antibodies that the mother makes are likely to cross the placenta, giving the baby protection against the flu before he can get his own vaccination at six months.
There’s no need to be concerned about mercury thimersol in the shots, as a thimerosal-free version will be available: “All you’ll have to do is ask for it,” says Dr. Charles Hux, a high-risk-pregnancy specialist in private practice. Besides, he adds the regular vaccine contains very little mercury—“the same amount as in one can of tuna fish.” Even the strictest advice for expectant mothers will allow that level of consumption once a week—and you only need the flu shot once a year.
Carmichael is a senior writer for NEWSWEEK.
