Damned if you do, damned if you don't.

October 10, 2006 9:58 AM

Pregnant women are advised to get the flu vaccine. Pregnant women are also advised to avoid mercury. The vast majority of the flu vaccine stock available in the US contains thimerosol. Should a pregnant woman get vaccinated with a flu vaccine that contains thimerosol? Does your answer vary depending on the stage of pregnancy?

Bonus question: if you think the woman should get vaccinated, do you also think that she should avoid tuna sandwiches? How much risk is too much risk when it comes to mercury exposure?

posted by crazycanuck to health & fitness (26 comments total)

Having just gone through this a few months ago...

We didn't get a flu shot for my pregnant wife. The doctor didn't even suggest it (in Canada).

When I asked about thimerosol in vaccines, I learned that in Canada they were removed from almost all vaccines. In this case I'd asked about them for the shots my new daughter was getting. In the course of the discussion I learned that Americans (my wife is one) can request thimerosol-free vaccines in the U.S.

Yes, avoid tuna. That's a pretty minor thing to do to ease you peace of mind. Plus there was a recent study showing that the levels in some tunas are much higher than the amount that was considered dangerous before. And avoid giving it to a kid under 5 or so too.
posted by Kickstart70 at 10:10 AM on October 10, 2006

Ask your doctor for a thimerosal-free flu shot, but do it sooner rather than later. Many vaccine manufacturers aren't producing thimerosal-free vaccines, citing a lack of proof that the mercury-based anti-bacterial causes any risk for autism (which, I assume, is your concern).

When it comes down to it, the risk of flu negatively impacting the health of your unborn child is larger than the theoretical risk of autism as a result of getting the flu shot with thimerosal.

Finally, direct from the CDC:

Is it safe for pregnant women to receive an influenza vaccine that contains thimerosal?
Yes. A study of influenza vaccination examining over 2,000 pregnant women demonstrated no adverse fetal effects associated with influenza vaccine. Case reports and limited studies indicate that pregnancy can increase the risk for serious medical complications of influenza. One study found that out of every 10,000 women in their third trimester of pregnancy during an average flu season, 25 will be hospitalized for flu related complications.

Additionally, influenza-associated excess deaths among pregnant women have been documented during influenza pandemics. Because pregnant women are at increased risk for influenza-related complications and because a substantial safety margin has been incorporated into the health guidance values for organic mercury exposure, the benefits of influenza vaccine with reduced or standard thimerosal content outweighs the theoretical risk, if any, of thimerosal.
posted by Merdryn at 10:22 AM on October 10, 2006

First off, tuna (and other fish/environmental hazards) contains methyl mercury - this is different from the ethyl mercury found in vaccines as a preservative.

You can ask for non-thimerosal preserved vaccine, as noted, limited stock may dictate a wait or a trip to a few different places - Our pediatrician offers thimerosal-free vaccine, a woman should check with her OB/GYN, I'd assume it's a fairly common question. The new nasal spray versions are thimerosal-free as well, though they are not approved for pregnant women.

As to the tuna, according to this PDF from the Minnesota Dept of Health, one flu vaccine dosage contains 12.5 micrograms of ethyl mercury, compared to 11 of methyl mercury in the average can of tuna. Given that just one can of tuna would be extremely unlikely to cause problems, I'd say:

Pregnant women in their third trimester should, if concerned, ask for thimerosal-free flu vaccine, but are almost certainly safe with a "normal" vaccine, especially given the significantly higher risk of flu complications vs. mercury poisoning (As I recall from my wife's experience, they won't give you a flu shot before the third trimester). They should probably avoid tuna and other fatty fishes, given cummulative ingestion/unknown amounts.
posted by jalexei at 10:35 AM on October 10, 2006

Sorry - found some documentation that states flu-vaccines are recommended for any stage of pregnancy - not sure if that's a geographic distinction.
posted by jalexei at 10:37 AM on October 10, 2006

Oh, for the love of...

Try here or here or here or here if you're concerned about thimerosal.

Let me make my point more clearly: the people who want you to worry about thimerosal are fools, and are peddling a brand of paranoia that is utterly unsupported by the actual scientific evidence.

Of course, any minute now we can expect an invasion from the tinfoil-hat crew on AskMe, who will mightily strive to obscure the issue (q.v. any thread involving, say, aspartame for a sample), but the scientific reality remains that thimerosal has not been proven to be unsafe. And there's been a lot of effort to do so.
posted by scrump at 10:52 AM on October 10, 2006 [3 favorites]

The FDA recommends limiting your intake of tuna to one can a week. Consumer Reports won't really make a recommendation, but they seem to suggest less is better. Environmental groups who aren't taking any shit from the tuna industry recommend even less.

As for the vaccine, I've never heard of any studies that show a particular danger from getting the flu during pregnancy. Docs used to get pretty freaked by pregnant women having fevers, but theres' spotty evidence that fevers are particularly dangerous in pregnancy.

I'd skip the vaccine and take lots of vitamin C during flu season.
posted by serazin at 10:53 AM on October 10, 2006

random link about fevers. Basically, tehre are no large scale studies confirming that fevers cause birth defects. Some anacdotal evidence indicates that fevers MAY cause neural tube defects very early in pregnancy - like in the first few weeks. At this point, I think you're fine.
posted by serazin at 10:55 AM on October 10, 2006

Get the flu vaccine; it's not dangerous and can help you immensely. Don't eat canned tuna.
posted by Justinian at 11:07 AM on October 10, 2006

scrump: While I don't disagree, what it came down to for me was this:

- minimal effort to avoid mercury
- rather extreme repercussions (an autistic child would certainly make me very sad) if what they say is even 0.01% true

Since I can just get non-thimerosol vaccines, and there is no reason to give my kid tuna, it's a pretty easy choice to make.
posted by Kickstart70 at 11:11 AM on October 10, 2006

if what they say is even 0.01% true

I would like to suggest that this "threat profile" is somewhat askew, and that there are far more productive things to be worrying about in terms of reducing risk.

Don't kid yourselves: if people really cared all that much about removing all risk from the life of their children, they wouldn't let them set foot in a motorized vehicle. Oops, but that would impact their lifestyles, wouldn't it? Better then to remove an infinitesimal risk, so they can feel like they're doing something even though they're not? Is that it?

The risk thimerosol may or may not pose is microscopic when compared to the risk of serious injury or death in a car accident. Amazing how many parents get all excited about thimerosol while packing the kids into the cargo area of their SUV for the drive to the movies.

Risk cannot be eliminated. Let me repeat that: Can not be eliminated, and being distracted by the irrelevantly tiny risks prevents you from making substantive changes that would address the huge risks around you every day. The time spent freaking out about thimerosol would be better spent checking the batteries in your smoke detectors for gods sake.
posted by aramaic at 11:35 AM on October 10, 2006 [3 favorites]

scrump - in medicine, the burden of proof falls on the potentially harmful intervention - not on the lack of intervention.

In other words, Themerisol does not need to be proven to be UNSAFE in order for us to stop using it - rather, it should be proven to be safe in order for us to start using it. Especially since mercury has been established as dangerous to neurological development and health (a fact that the FDA takes into account when it recommends limiting fatty fish intake, and that drug companies considered when they removed themerisol from most childhood vaccines) only supports the idea that we should be cautious about this additive.

weak wikipedia entry on the Precautionary Principle.
posted by serazin at 12:12 PM on October 10, 2006 [1 favorite]

scrump gets best answer for the Slate links explaining the difference between ethyl mercury and methyl mercury. I was not aware of this difference. I would have marked jalexei as well, but the FluMist spray is definitely not recommended for pregnant women as it contains live flu virus.

For what it's worth, I have been requesting a themerisol-free vaccine but I have not been able to find a source. I will vaccinate anyway if I can't find one.
posted by crazycanuck at 12:13 PM on October 10, 2006

It's amazing that since the arrival of a flu vaccine, people have become rabid about not getting flu. Flu for the majority of people is not dangerous - yet I see people not in any risk group clammoring for it like it will stop their very death.

Flu isn't considered dangerous in pregnant women - at least not from the doctors of a friend or two I asked. I would rather avoid the flu shot and risk getting flu (how likely is it you'll get flu?) than take the shot and worry about the shots risk.
posted by agregoli at 12:23 PM on October 10, 2006

Um, one reason to get the shot that's not often discussed is this: whether or not you personally get the flu is irrelevant. Whether or not you get the flu and then pass it on to twenty other people is relevant.

...because not all of them may be so lucky as to consider it a mere inconvenience. But hey, far be it from me to tell people they shouldn't be selfish. Just realize that you'll be contributing to the spread of a preventable illness that kills people. Maybe you're OK with that.
posted by aramaic at 12:39 PM on October 10, 2006

The Harvard Medical School's conclusion about tuna was that the benefits of it were clear and well defined enough to outweigh the more abstract risks and they encouraged mothers to eat it.

The thiomersal thing is definitely interesting and I'm not sure why there's not a better-defined way for people in the hypothetical risk group to get single-dose shots that don't use it. Or perhaps there are, but the marketing powers that be don't want to talk about it lest they further whip up the frenzy. I would imagine that an OB/Gyn would know about it if it exists....
posted by phearlez at 12:52 PM on October 10, 2006

"Flu isn't considered dangerous in pregnant women"

This is simply not true. Pregnancy is a time of reduced immunity, so if you get the flu, you're at much higher risk for serious complications that could affect the fetus. In fact, pregnant women are much more likely to be hospitalized with the flu than women who are not pregnant.

I know the American College of Obstetrics and Gynecology recommends the flu shot for any woman who will be in her second or third trimester during the flu season. Here's a document from them on the various immunizations, their risks and implications. Hope this helps.
posted by Sully6 at 1:05 PM on October 10, 2006

I was told in child development class that flu during pregnancy may increase risk for the child developing schizophrenia later in life.
posted by xo at 2:30 PM on October 10, 2006

Flu isn't considered dangerous in pregnant women

Absolutely false.

From the second link:

Influenza vaccination is the primary method for preventing influenza and its severe complications. As indicated in this report from the Advisory Committee on Immunization Practices (ACIP), annual influenza vaccination is now recommended for the following groups (Box):

• persons at high risk for influenza-related complications and severe disease, including
  • children aged 6--59 months,
  • pregnant women,
  • persons aged >50 years,
  • persons of any age with certain chronic medical conditions; and
• persons who live with or care for persons at high risk, including
  • household contacts who have frequent contact with persons at high risk and who can transmit influenza to those persons at high risk and
  • health-care workers.

posted by scrump at 3:14 PM on October 10, 2006

scrump - in medicine, the burden of proof falls on the potentially harmful intervention - not on the lack of intervention.

In other words, Themerisol does not need to be proven to be UNSAFE in order for us to stop using it - rather, it should be proven to be safe in order for us to start using it.
posted by serazin at 12:12 PM PST on October 10

It has been proven to be safe, you fucking dolt. How many studies do you want? Are a dozen not enough? Why not? Will you not be happy until every fucking human being on the planet has participated in a thimerosol study? Because we're actually pretty goddamn close to that point.
posted by Optimus Chyme at 6:39 PM on October 10, 2006

Wow! Raising the bar on quality of discussion around here! Gotta love it!


I get that many experts recommend flu vaccine. I don't get any high quality medical studies that actually show an increased risk to the fetus or mother with flu during pregnancy. Even increased hospitalization proves nothing except that doctors, who we know are concerned about the flu, admit pregnant women to the hospital at higher rates than non-pregnant women.

Since flu is considered dangerous in pregnant women, cautious doctors will hospitalize pregnant women at higher rates. Are pregnant women at more risk? This has not been established.

As far as I understand it, Thimerisol only came into near universal use in childhood vaccines in the 80s, so there's no way to be sure of long-term safety yet.

Love, "fucking dolt"
posted by serazin at 12:03 AM on October 11, 2006

And FYI (and I'll stop commenting after this) I never said that thimerisol causes autism - good studies strongly contradict that possibility. But Thimerisol was never subjected to the kind of testing that newer drugs go through (including animal trials etc) and so we have never rigerously studied all of it's effects. (and yup, this is also true of asprin, but since human's have been using aspirin since what - the the time of Ramses of Egypt?, I feel pretty OK about it). For that reason, I personally would not (and did not) chose to get a flu vaccine during pregnancy.

xo
posted by serazin at 12:09 AM on October 11, 2006

Sorry if I'm considered "selfish" if I don't get a flu shot - first of all, other people's health by possibly catching something I've got isn't my concern. I practice standard hygenic practices (sneezing into my sleeve, washing hands well, etc.) so I don't know what else I can be required to do.

Secondly, I can't get a flu shot because I'm allergic to eggs.

And thirdly, I wouldn't get one any way because I personally believe they are fucking stupid and I never get flu anyway. But to each their own.
posted by agregoli at 2:22 PM on October 11, 2006

serazin, I don't think you're a dolt but I confess to not totally understanding where you're coming from. I'm preggo myself, so this isn't just academic for me.

I think you would agree that (1) pregnant women have a dampended immune system and (2) pregnancy taxes the pulmonary system--blood volume increases, that sort of thing. Thus, I would say the risks during pregnancy are higher for both contacting the flu and suffering from complications than for women who are not pregnant.

There was a large epidemiological study reported in 1998 that reviewed 17 years' worth of flu season data and found that pregnant women were several times more likely to be hospitalized with heart and lung complications from the flu than other women. This wasn't simply "Oh, hey, she's pregnant, stick her in the hospital until she gets better" but true morbidities associated with the illness.

Some estimate the rate of infection during the flu season at 10-20% in the general population. While I can't ever recall having the flu myself, two years ago I was one of only a handful of people in my office who wasn't affected by an outbreak. Folks who never took a sick day in their life were out for two weeks; others ended up in the hospital. The real flu--not just a cold--is seriously bad stuff and I'm just not comfortable with a 10-20% chance when staying healthy is so crucially important during this time.
posted by Sully6 at 6:48 PM on October 11, 2006

Thanks sully6 for a thoughtful response!

I have a four year old now after a very normal and then suddenly very abnormal pregnancy. My water broke at 33 weeks and I spent 3 weeks on bedrest praying for the best. So ya, I know what it is to make these difficult decisions that involve weighing risks in pregnancy.

Anyhow, I'd be interested to see this study you're talking about, although it sounds like it was a review of the literature which has flaws compared to a large scale clinical trial. None of the links re: flu and pregnancy in the above discussions reference any medical studies either. The fact that pregnant women are diagnosed with and hospitalized for lung complications still doesn't mean much to me without seeing details of her symptoms and diagnosis - and does not confirm whether the symptoms of pregnant women were actually more severe than the general population. so again, I don't think we have confirmative data of anything beyond the fact that doctors are more likely to admit a pregnant woman with the flu than a non-pregnant woman.

Pregnant women and doctors are very concerned about something terrible happening to themselves or to their developing babies. Sooo, doctors and pregnant women tend to fall on the side of more intervention rather than less during pregnancy. But these interventions are rarely proven to improve outcomes. A perfect example is routine fetal monitoring. It's never been proven to improve outcomes, in fact, it increases cesarean rates (another retrospective review of the literature but one that I trust because of the specific way they are tracking information), yet, routine fetal monitoring is derigour in almost every hospital in north america.

While no one likes having the flu, and the flu is dangerous, we don't have sound science that shows that the flu vaccine is safer than having the flu during pregnancy. Since the flu has been around for millions of years and the flu vaccine has been around for less than 100 (less than 50?), I'm going to take my chances with the flu.
posted by serazin at 7:50 PM on October 11, 2006

Serazin, you're seriously not sure if the "flu vaccine" is safer than having the flu during pregnancy? There is virtually no danger to the flu vaccine unless you're allergic to eggs, so how could it not be safer than catching the flu? You also seem to be rejecting out of hand anything that contradicts your position. Here:

Neuzil KM, Reed GW, Mitchel EF, Simonsen L, Griffin MR. Impact of influenza on acute cardiopulmonary hospitalizations in pregnant women. Am J Epidemiol 1998; 148:1094-102.

You can read the whole study there for free, I believe.

Oh, and gangrene has been around for millions of years and vancomycin has been around for less than 100 years, but would you prefer to take your chances with gangrene? Ditto for high blood pressure and beta-blockers. Or cancer and gamma-knife surgery.
posted by Justinian at 6:57 AM on October 12, 2006

I don't have time to read that whole study, but as far as I can tell from skimming, the way that they determined whether someone was hospitalized for flu was whether or not they were hospitalized during flu season. As far as I can tell, mortality rates were not increased amoung the pregnant study 'participants' (not really participants since we're only reading old medical charts here). As I said, I didn't read the whole article, so maybe I'm wrong.

Note that the text states "White ethnicity, residence in a non-urban area, and
being in the blind/disabled enrollment category were
demographic factors associated with an increased risk
of hospitalization." Suprise! who gets admitted to the hospital is somewhat ARBITRARY! White people get hospitalized more than black people in this study - does this mean that white women get the flu more than black women? Probably not. It probably means that doctors, with their indidvidual set of biases, and for whatever reasons, admit women at different rates based primarily on the race of these women.

All this study shows is that doctors admit pregnant women to the hospital for flu at higher rates than non pregnant women. No suprise here: since doctors believe flu is more dangerous for pregnant women, they admit them to the hospital at higher rates.

And nope, I don't think antibiotics are more dangerous than gangrene (at least not when you state it in simple terms that relate to a specific individual - since measuring the overall health impact that routine use and overuse of antibiotics has had on the human and non-human population of this planet is difficult but might lead to a different conclusion). My point is that Theomerisol in specific was not subject to modern or rigerous scientific testing (beta blockers and vancomycin were) and so we don't actually know much about it. And even drugs that have been subject to extensive testing may show dangerous effects with long term or widespread use.

Look, to be honest, even though there is no clear science on this, I think you're probably right: chances are good that an individual pregnant woman is more likely to have complications from the flu than from flu vaccine. I made a personal choice not to get the vaccine, and I'm basically trying to convey what my thinking was around that issue.
posted by serazin at 10:00 AM on October 12, 2006