How would pulling 6 g's on a daily basis affect an unborn child at all
stages of pregnancy? What would 9 g's do?

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Clarification of Question by f16chevy-ga on 18 Feb 2005 17:06 PST

That's funny

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Request for Question Clarification by librariankt-ga on 06 Mar 2005 19:55 PST

Hey there - 
In all seriousness...

I did a few searches in MEDLINE to try to find you something, but came
up pretty short.  Using the search:
"Military Personnel"[MeSH] AND ("Pregnancy"[MeSH] OR "Fetus"[MeSH] OR
"Abortion, Spontaneous"[MeSH]) AND (gravit* OR air OR pilot OR fly OR
airplane)
I got 13 results, of which only one looks even relatively decent -
unfortunately it's in Russian and not available to me even if I did
speak the language (though I can give you the citation if you'd like
it).

I'm going to try another tack tomorrow if you're still interested in
an answer to this question.  I seem to remember some research done on
roller coasters and pregnancies.

There's also quite a bit of research that's been done on pregnant and
lactating rats in hypergravity environments - of course, that's
defined as a sustained 2G situation.  If those would be helpful I can
dig up some review articles for you.

Librariankt

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Clarification of Question by f16chevy-ga on 07 Mar 2005 14:08 PST

Whatever you can find would be great. I can't believe there aren't
medical websites where people can ask specific medical questions and
get a professional to answer.

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Request for Question Clarification by byrd-ga on 16 Mar 2005 15:01 PST

Hi f16-chevy!

I saw your question earlier, but didn?t have the time to do the
researching I wanted to for you. However, though I've now found - and
spent - considerable time at it, I'm afraid the news is that there
really does not appear to be much information available, at least
online, about pregnancy and G-forces. I suspect  this dearth of
information may be due in no small part to the unfeasibility of
putting pregnant subjects through centrifuge tests, let alone in
actual flight for testing purposes.

However, I have found a little, and would like to share it with you,
though since it doesn?t answer your question as asked, I?ll post it
here instead of in the answer box. By posting it here instead of as a
comment, you will receive an email notice.

First of all, you'll need Adobe Acrobat Reader to read any of the
above files that are in pdf format.  If you don't have it, you can
download it for free, here: 
http://www.adobe.com/products/acrobat/readstep2.html

I?m sure during your training you were given information on the
general physiological effects of high g-loads. Still, it might be well
to just refresh yourself on those factors, and then try to extrapolate
those to include a developing fetus. Here are a few links that look
helpful for such an exercise:

This article is about orthostatic hypotension (temporary drop in blood
pressure) as experienced by astronauts returning to earth?s gravity,
but has implications for fighter pilots as well with regard to the
high g-forces they experience:
http://www.firstscience.com/SITE/ARTICLES/dizzy.asp  

There?s a good overview here from a June 1998 Airman magazine article
entitled, ?The Spin Doctors,? by Tech. Sgt. Pat McKenna. The
descriptions are very vivid.
http://www.af.mil/news/airman/0698/spin.htm 

Here?s an abstract of an interesting study on the effects of G-forces
on women, as modified by the use of both older and newer G-suits:
?Cognitive performance and physiological changes in females at high G
while protected with COMBAT EDGE and ATAGS.? Zhang L.. Department of
Biomedical and Human Factors Engineering, Wright State University,
Dayton, OH 45435-0001, USA. lzhang@cs.wright.edu
You can find it at PubMed, but will have to pay to read the full text
of the article if you?re interested: 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10503749&itool=iconabstr

This short paragraph addresses the effects of g-forces on women in particular: 
?Because women have a smaller body mass the shorter distance between
their heart and brain makes it easier for them to counteract the
G-forces. Advances in centrifuge technology and training , special
exercises, and newer G-suits are making marked improvement in aircrew
G-tolerance.?
From ?Debunking Rumors, Fallacies, Legends, Gossip, Fables, Nonsense. 
Section 6, ?The "women pilots and astronauts can't take the G-forces"
claim?
http://userpages.aug.com/captbarb/myths.html 

=====================================================================

As to information about the effect of high g-forces on a pregnant
women, and/or her fetus in particular, there really is very little.
Here?s what I was able to find:

This article by a femal Air Force officer says in part, ?Research has
shown that pregnant women have a reduced G tolerance, due to the
stresses placed on their bodies during pregnancy.?
From ?The Aviatrix in Military Aviation? by 2Lt Katrine M. Waterman
Published 10 Oct 01 in Air & Space Power Chronicles
http://www.airpower.maxwell.af.mil/airchronicles/cc/waterman.html 

And this Australian source states, ?The effects of accelerative forces
on the foetus have not been established despite theoretical concerns
expressed of a bungy jumping foetus!  Physiologically one woud predict
effects on placental blood flow and placental integrity may be of
conern here.?  Fast women: Or why women who fly high performance
aircraft are fast but not loose.?  T.L. Smart,  Australian Military
Medicine, Volume 7 Number 1, April 1998 .
http://www.ctie.monash.edu.au/hargrave/fast_women.pdf 

And finally, this article from an AvWeb contributor says, ? ... the
pressure of the uterus on the pelvic venous structures during
high-positive Gs will induce Gloc (G-force-induced loss of
consciousness) much sooner.?
?Pregnant Pilots And A Look At LASIK,? Brent Blue M.D. AvWeb Nov. 15, 2000. 
http://www.avweb.com/news/aeromed/181801-1.html 

=====================================================================

Finally, though I?m pretty sure you?re already aware of this, just to
round things out, here are a few snippets from the regs of the U.S.
Air Force and Coast Guard, as well as the Australian Air Force that
make it clear they consider it unsafe for a pregnant women to be
subjected to the stresses of flight, particularly high gs as implied
by the prohibition against flying ejection-seat aircraft while
pregnant:

?Pregnant women will not fly in ejection-seat aircraft .....? 
AETC Supplement 1, AF Instruction 11-401, Section 1.9.4.7.1.6.10.7 1,  Jan 2002
http://www.keesler.af.mil/A76pubs/Appendix%20A%20Publications/Instructions%20and%20Regulations/AFI11-401_AETCSUP1.pdf

Coast Guard guidelines: ?...Flight personnel are grounded during
pregnancy unless a clearance to continue in flight status is granted
....?  From the ?Coast Guard Aviation Medicine Manual,? Chapter 11
Pregnancy, Section A: Pregnancy in Aviation Personnel
http://www.uscg.mil/ccs/cit/cim/directives/CIM/CIM_6410_3.pdf 

?Pregnancy, particularly during the final trimester, is a cause of
temporary unfitness to exercise the privileges of all aviation
licences ....?
?Designated Aviation Medical Examiners Handbook,? Section 2.8.3 Pregnancy. 
http://64.233.161.104/search?q=cache:Mt9AJt0PxL8J:www.casa.gov.au/manuals/regulate/dame/080rfull.pdf+flight+aeromedical+pregnancy+g-forces+aspects+OR+factors&hl=en
 

I did look for some information on both aerobatic flying, which also
subjects a pilot to high g-forces, as well as amusement park rides,
and came up as empty on both as I did searching on information
pertaining to female fighter pilots.

I used both ://www.google.com and http://scholar.google.com for
searching.  Here are the terms I ultimately found most ?helpful? if
you?d like to try to continue this search on your own:

[women "fighter pilots" pregnant OR pregnancy]
[pregnancy flight]
[g-forces fetus OR "pregnant pilot" OR pregnancy]
[G-forces pregnancy "flight physiology" OR "aeromedical factors" OR
aviation OR aeromedical]

Here are links to a couple of the best search returns:
://www.google.com/search?num=20&hl=en&lr=&safe=off&c2coff=1&q=G-forces+pregnancy+%22flight+physiology%22+OR+%22aeromedical+factors%22+OR+aviation+OR+aeromedical&btnG=Search

://www.google.com/search?q=g-forces+fetus+OR+%22pregnant+pilot%22+OR+pregnancy&btnG=Search&num=20&hl=en&lr=&safe=off&c2coff=1

I?m sorry; I wish I?d been able to find more.  My suggestion in light
of your comment is that, until more information becomes available, it
might be a good idea for you and your husband to be exceptionally
carefull to avoid any possibility of a ?whoops? pregnancy.

Best wishes,
Byrd-ga

They did this with chickens - the chickens had really fat legs.

Fat legs...or flat eggs?

Fat eggs or was that Flat legs....  now I'm confused.  I do know it
had something to with chickens..

Oh you guys are a wealth of information!

I would look up the incidences of miscarriage among pilots.

Ask your flight surgeon, they should have this information published somewhere.

Thanks. Our flight surgeons aren't as knowledgable as one may think

I would have thought that this information would be available, and
that at least one flight surgeon with an inflated ego would have
studied such a thing.

Check back here in a couple days and I'll see what I can dig up.

bob

Air travel in pregnancy.     Huch R    Klinik fur Geburtshilfe,
Departement fur Frauenheilkunde, Universitatsspital Zurich     
Zeitschrift fur arztliche Fortbildung und Qualitatssicherung : in
Zusammenarbeit mit der Kaiserin-Friedrich-Stiftung fur das arztliche
Fortbildungswesen  (1999 Oct),  93(7),  495-501

Women who fly during pregnancy, whether as passengers or crew,
continue to fuel the debate over the potential impact on pregnancy
outcome and fetal development, the two risk factors most commonly
invoked being relative hypoxaemia due to the decreased cabin pressure
and, more recently, cosmic radiation.  On both theoretical and
experimental grounds (altitude physiology and studies in pregnant
women during flight), commercial flight poses no threat to the fetal
oxygen supply in a normal pregnancy.  As for cosmic radiation, only
theoretical estimates are available of flight crew exposure: if annual
doses approximate to background at ground level (3-5 mSv), the dose
received during an individual pregnancy can be estimated from the
fraction of annual flight time spent while pregnant.  It is doubtful
whether any epidemiological study could ever confirm or refute this
theoretical estimate of a low increase in risk.  Many airlines have
opted to allow pregnant crew to continue flying.  There is thus little
if any ground for advising against passenger flight in pregnancy. 
Flying is probably the safest and most comfortable way to travel
long-distance in pregnancy.  The few relative contraindications
include flying close to term, a history of miscarriage and premature
delivery, heavy smoking, severe anemia, cardiopulmonary disease, and a
serious fear of flying.

so,,, i'm tapped out. 

i don't think you'll find much about g-forces,  but i would look more
at studies involving physical exertion among pregnant women athletes.

Dr.Bob,

Thanks for the information. I will look into how it affects "female
athletes". I agree that one would think that there would be some
flight surgeon out there that needed another OPR bullet or early
promotion. Maybe I'll have to do my own research! j/k! My only concern
is if my husband and I have a "whoops pregnancy" and I don't realize
it for a month or two. catch my drift? Thanks for your help.