Seriously? Get a vaccine to prevent still-birth??? - Mothering Forums
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#1 of 16 Old 05-24-2012, 07:01 PM - Thread Starter
 
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http://www.nydailynews.com/life-style/health/flu-shot-offers-surprising-benefits-expecting-moms-reduced-risk-stillbirth-preterm-birth-birth-weight-article-1.1083865?localLinksEnabled=false


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#2 of 16 Old 05-24-2012, 07:59 PM
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I find these conclusions unconvincing.  As a pro-vaxer, I think it's nice to know that studies show that this particular flu vaccine is low-risk for pregnant women.  However, this article offers no explanation of how or why vaccinating against the flu might protect against pregnancy outcomes that seem unrelated to flu - I think they might have just discovered that women with access to comprehensive health care are more likely to get flu shots and less likely to face certain adverse outcomes of pregnancy. 

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#3 of 16 Old 05-24-2012, 09:30 PM
 
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#4 of 16 Old 05-24-2012, 09:35 PM
 
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Going with the idea the it's not the FLU vaccine.  Leaving it at that.  Most data points to no. 

 

Thanks Taxi and Stik for the links.

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#5 of 16 Old 05-25-2012, 02:12 AM
 
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Originally Posted by stik View Post

I find these conclusions unconvincing.  As a pro-vaxer, I think it's nice to know that studies show that this particular flu vaccine is low-risk for pregnant women.  However, this article offers no explanation of how or why vaccinating against the flu might protect against pregnancy outcomes that seem unrelated to flu - I think they might have just discovered that women with access to comprehensive health care are more likely to get flu shots and less likely to face certain adverse outcomes of pregnancy. 

 

 So I found this quite interesting, and definitely presented problematically in the media ("flu shot prevents still birth" is a complete oversimplification of the findings). I'm still trying to get access to the full text of the article (might be able to get it through my uni library, even though this is not actually my research area), but I did get the abstract (from here http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2011.300606 and copied below)

 

From this it seems that the problem stik mentioned does apply. It looks like they just took the rates of still birth etc. for the vaccinated and unvaccinated women in the sample and compared them. What they should do is to take rates for vaccinated and unvaccinated women who otherwise have access to the same medical care. Now if I understand Canadian medical system, the discrepancy between the best and the worst health care will not be as large as in the US, but there will still be women who don't bother to get enough medical care during pregnancy, and they are both more likely to be unvaccinated and more likely to have complications which are not picked up an treated, so they will bias this study in the sense of increasing the likelihood of problems in the unvaccinated group. 

 

Still it's interesting that they saw such a large effect in the sense that those who were vaccinated were less likely to have problems. That does at least suggest to me that there's no serious additional risk of miscarriage introduced by getting the H1N1 vaccine during preganancy. Which I agree is in complete contradiction to the reports of the studies taximom5 posted (so I'll get to fact checking of those when I can!). 

 

Fair disclosure (plus an anecdote!) - I got the H1N1 vaccine in 2009 (in the UK) when I was pregnant with my son. He was born full term and healthy and is developing great. Neither of us got sick with H1N1, although it did make my arm pretty sore for a couple of days.  

 

 

 

 

 

Quote:

 

H1N1 Influenza Vaccination During Pregnancy and Fetal and Neonatal Outcomes

 
Deshayne B. Fell, MSc, Ann E. Sprague, PhD, Ning Liu, MSc, Abdool S. Yasseen III, MSc, Shi-Wu Wen, PhD, Graeme Smith, MD, PhD, and Mark C. Walker, MD, MSc, for Better Outcomes Registry & Network (BORN) Ontario

Read More: http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2011.300606

 

Objectives. We evaluated the relationship between maternal H1N1 vaccination and fetal and neonatal outcomes among singleton births during the 2009–2010 H1N1 pandemic.

Methods. We used a population-based perinatal database in Ontario, Canada, to examine preterm birth (PTB), small-for-gestational-age (SGA) births, 5-minute Apgar score below 7, and fetal death via multivariable regression. We compared outcomes between women who did and did not receive an H1N1 vaccination during pregnancy.

Results. Of the 55 570 mothers with a singleton birth, 23 340 (42.0%) received an H1N1 vaccination during pregnancy. Vaccinated mothers were less likely to have an SGA infant based on the 10th (adjusted risk ratio [RR] = 0.90; 95% confidence interval [CI] = 0.85, 0.96) and 3rd (adjusted RR = 0.81; 95% CI = 0.72, 0.92) growth percentiles; PTB at less than 32 weeks’ gestation (adjusted RR = 0.73; 95% CI = 0.58, 0.91) and fetal death (adjusted RR = 0.66; 95% CI = 0.47, 0.91) were also less likely among these women.

Conclusions. Our results suggest that second- or third-trimester H1N1 vaccination was associated with improved fetal and neonatal outcomes during the recent pandemic. Our findings need to be confirmed in future studies with designs that can better overcome concerns regarding biased estimates of vaccine efficacy.


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#6 of 16 Old 05-25-2012, 02:42 AM
 
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So both of these links seem to be press coverage of the same report made by the National Coalition of Organized Women to the CDC. 

The second one provides this link to a page with a series of other links to things: http://www.progressiveconvergence.com/H1N1-RELATED%20miscarriages.htm including the press release both of the above articles are based on (and are almost exact copies of in places - a common practice to be fair with science media). 

 

Neither of these is based on an actual scientific study, although they (in my opinion) try to look a bit like one. They use two sources to search for miscarriages following H1N1 vaccines - one is VAERS (which has been previously discussed on these boards, is a place where you or your Doctor can report a vaccine reaction, and is most likely not complete and also is open to false reporting, so could have numbers biased either high or low). In that database they say they found 219 reports of miscarriages soon after H1N1 vaccines. The other source of data was a solicitation by the National Coalition of Organized Women for women who has miscarriages following the H1N1 vaccines. That had 72 (heartbreaking) reports.

 

I don't understand how they get from those 291 reports of miscarriages to a figure of a 700% increase in miscarriages caused by H1N1. The number they cite of 1588 miscarriages caused by H1N1 (and maybe as high as 3587) seems to have come out of nowhere. And what's curious actually is that it's so low. Sadly 15-20% of pregnancies end in miscarriage. In the H1N1 season the CDC estimated 38% of pregnant women got the vaccination. The total number of pregnant women in the US is about 4 million each year, so that's 1.5 million women who were pregnant and got vaccinated, and you'd expect (sadly) at least 228,000 of those pregnancies to end in miscarriage, and if you assume the rate is even across 9 months, and "soon after H1N1" means within 2 weeks of the vaccine that in my estimate gives 12,666 spontanous miscarriages for women in the 2 weeks following their H1N1 vaccine.... 

 

 

(FYI I got some of those numbers from a blog post skeptically analysing the report but as it is not very respectful of anti-vax viewpoints and I'm trying here to skeptically analyse the report in a respectful way I won't link in here. I found it by Googling "national coalition of Organized Women report on h1n1" but also be warned my version of Google may be different to yours). 

 

In my opinion this study is worthless, and has been pushed by Eileen Dannemann who has started (and may be the only member of?) the National Coalition of Organized Women to sound like she's representing a lot of women and try to give weight to invented data which scares women off getting the H1N1 vaccine while pregnant. I know a lot of the rest of you posting here will disagree with that statement, but that is my opinion of this report. 


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#7 of 16 Old 05-25-2012, 06:27 AM
 
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Quote:
Originally Posted by stik View Post

  However, this article offers no explanation of how or why vaccinating against the flu might protect against pregnancy outcomes that seem unrelated to flu - I think they might have just discovered that women with access to comprehensive health care are more likely to get flu shots and less likely to face certain adverse outcomes of pregnancy. 

 

I don't disagree with anyone…I think the article is dung.  The title in particular is misleading. 

 

However, the study they looked at came out of Ottawa.  If they were looking at Canadian women, they all (or almost all - barring obstacles to getting to the clinic) have access to health care.  We have universal health care.  

 

I suspect the findings relate to the fact that perhaps those who actively seek health care are probably healthier than those who do not.  Conscientious non-vaxxer and sel/del aside .…but we suspect those account for only a small percent of non-and under vaxxed.

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#8 of 16 Old 05-25-2012, 07:34 AM
 
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I agree that the conclusions described in the news article seem like a reach, and the headline is blatantly over the top. 

 

That said, any well designed study should have controlled for the idea that people who seek flu vaccination while pregnant also practiced other beneficial health behaviors. This is a well known and thoroughly acknowledged source of bias in health research. Without access to the full text, I have no idea if this was addressed, but if it was not, the article shouldn't have made it through peer review.

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#9 of 16 Old 05-25-2012, 07:43 AM
 
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Originally Posted by bmorehon View Post

 

 

That said, any well designed study should have controlled for the idea that people who seek flu vaccination while pregnant also practiced other beneficial health behaviors. This is a well known and thoroughly acknowledged source of bias in health research. Without access to the full text, I have no idea if this was addressed, but if it was not, the article shouldn't have made it through peer review.

 

"Researchers from the University of Ottawa in Canada examined data from more than 55,000 child births in Ontario during an outbreak of H1N1, comparing mothers who were vaccinated to those who weren't."

 

The above line seems to point to the fact the research was from epidemiological study rather than from a double blind study.

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#10 of 16 Old 05-25-2012, 07:46 AM
 
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Has anyone found a link to the actual study?

I'm wondering if they looked at miscarriage rate (as opposed to stillbirth rate).

 

If the number of miscarriages was significantly higher WITH the flu shot (as has been reported by other organizations), that might partially explain why there were fewer stillbirths and fewer babies born with low birthweight.

 

And, as is always the case with studies, if women who had stillbirths/miscarriages/low birthweight babies were excluded from the study for other reasons (such as history of vaccine reaction, seizure disorder, autoimmune disorders, etc), that would also affect the results of the study.

 

As they always say, you can control the results of the study by controlling who is in the study.

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#11 of 16 Old 05-25-2012, 08:06 AM
 
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Originally Posted by kathymuggle View Post

 

"Researchers from the University of Ottawa in Canada examined data from more than 55,000 child births in Ontario during an outbreak of H1N1, comparing mothers who were vaccinated to those who weren't."

 

The above line seems to point to the fact the research was epidemiological rather than from a study.

Regardless of the study design, they should have controlled for this.  The quote above says they "examined data" - without access to the fulltext, I have no idea what data they examined, but even a basic chart review could have given adequate information.  At the very least, they should have controlled for smoking, weight or BMI, and access to/seeking of prenatal care - all of these are considered good proxies for a "healthy lifestyle" and should be included in any patient chart.

 

This abstract also doesn't mention exclusions, but if they excluded broad categories of high-risk women, that should be clearly mentioned in the abstract. 

 

Sorry for all the "should"s - this is why paywalls suck. I'm just making the point that the potential weaknesses being mentioned are well known and generally addressed in statistical analysis. 

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#12 of 16 Old 05-25-2012, 08:17 AM
 
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Found some further links.  Have fun!  I have not read them but they appear to be original source.

 

http://ajph.aphapublications.org/doi/abs/10.2105/AJPH.2011.300606?journalCode=ajph

 

http://www.media.uottawa.ca/mediaroom/news-details_2594.html

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#13 of 16 Old 05-25-2012, 09:01 AM
 
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^^^That's just the abstract. I have institutional access and have gotten ahold of the full text, so I'm going to peruse it and post what I think. (I'm skeptical for the reasons stik mentioned, myself.)

 

One small quibble: an analysis of epidemiological data is still a "study". Studies can be retrospective (looking back at events that already happened), which this one was.
 

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#14 of 16 Old 05-25-2012, 12:44 PM
 
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Quote:
Originally Posted by erigeron View Post

 

One small quibble: an analysis of epidemiological data is still a "study". Studies can be retrospective (looking back at events that already happened), which this one was.
 

 

Are you trying to correct me?  duck.gif

 

I will honour your quibble and will reword to use more precise language.

 

Too bad it is just the abstract.  It still offers more info than the nydailynews article.  Ex:  it said the following, which may point to bmorehon being correct in her assumption:

 

BORN includes demographic data that allowed the research team to correct for smoking, education and income; however, as with any population-based study, it may not be possible to account for all influencing factors.

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#15 of 16 Old 05-25-2012, 01:38 PM
 
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Yeah, studies come in many varieties. bouncy.gif http://en.wikipedia.org/wiki/Clinical_study_design for an overview of the different considerations.

 

I've finished reading the study and gathered some thoughts on it.

 

 

 

Study population: All singleton hospital births >20 weeks gestation and >500 g between Nov. 2, 2009 and Apr 30, 2010. 55,000 births (exact number is the same as mentioned upthread.
Used province-wide database that included all hospital births.
Did not include home births (they note that less than 2% of births in Ontario take place at home).
Most women were immunized in 2nd or 3rd trimester, based on the date that the vaccination program started and the dates of the births.

 

Outcomes: Looked at preterm birth (PTB) before 37 weeks as well as very early PTB (before 32 weeks), small or very small for gestational age, 5 minute Apgar <7, and fetal death at >=20 weeks gestation
Confounders: maternal age, parity (how many children they have had), smoking, maternal comorbidities, pregnancy complications, intrapartum complications, hx of preterm birth, chronic hypertension
Analyzed socioeconomic status by looking at the postal codes that the moms lived in. (I'm not Canadian, so I don't know how big a postal code is and how broad a socioeconomic spread it might have). They also analyzed neighborhood education level, presumably using the same method.
They state that they considered all these different factors as confounders if the factor is associated with a given outcome in the literature and if the factor was correlated with H1N1 vaccination. So if better-educated and more well-off women are less likely to have these complications and also more likely to be vaccinated, they considered that.

42% of study group received H1N1 vax. Most of these did *not* also receive seasonal flu vax.
No statistical association w/ reduced PTB but there was with very early PTB (<32 wks)
more moms with comorbidities were vaxed (which makes sense since they're probably getting more medical care in general)

 

There were fewer stillbirths in H1N1 group, and this held when subgroup analyses were done taking into account all the confounders mentioned before.
They did do analyses controlling for these various confounders and stated that their results were borne out in these more homogenous groups (i.e. of all moms with similar medical profile and similar socioeconomic group).

Discussion: they note that it's always hard in observational flu vaccine studies to know if the differences in outcomes are due to some difference in populations getting vaccinated. They think this study has less of that bias than most studies of the elderly because pregnant women as a group are young and mostly healthy. Nevertheless, they say their results could be due to some other confounder that they weren't able to tease out.

 

They think that the reduction in stillbirths is probably due to some factor having to do with fewer flu infections, but note that they couldn't track who actually got the flu or when precisely they were vaccinated relative to the birth. The study authors consider their results preliminary and say that more prospective trials need to be done (retrospective trials, like this one, look backwards; prospective trials are considered better because they are set up in advance and specifically recruited for, and there are better controls and less hindsight bias). They also note that during the H1N1 season the vaccine was very well-matched to the circulating strain of flu, and that isn't always the case, so this shouldn't necessarily be extrapolated to other flu seasons. They note that since most of these mothers were vaccinated in the 2nd or 3rd trimesters, the results shouldn't be extrapolated to vaccination in the 1st trimester.

 

 

The media (as they typically do) took what is imo a pretty well-done study and ran with it--they simplified it to the point where you can't even really tell what the results were from the coverage, and made it out to say things that the authors never claimed.

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#16 of 16 Old 05-26-2012, 01:31 PM
 
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Erigeron - thanks so much for posting that review, that was extremely helpful.

 

 

 It really looks like they've done all they could reasonably have been expected to to correct for the obvious bias of unvaccinated pregnant women having worse health care during pregnancy (on average). What an interesting study.....   


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