Safe to take a pregnant lady flying?

RyanB

RyanB

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Someone i know that is pregnant is interested in going for a local ride, shes about 8 weeks along, is it safe to have her fly?
 
Generally ok if all is normal. Always ask the OB/GYN, especially later term.
 
Ryanb said:
Someone i know that is pregnant is interested in going for a local ride, shes about 8 weeks along, is it safe to have her fly?
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8 weeks is nothing. a near term pregnancy is a little more trouble. but nothing about the flying affects pregnant women.
 
No problem especially that early. I flew with my wife during her first pregnancy, and she goes up with me now too. She is currently about 18wks in. I would avoid going way up high, and maybe in the last month or two, but otherwise its no big deal.
 
Confirm with the OB, but no issues. My wife flew up until about 7 months, and the only reason she stopped is because I stopped, too. We planned a trip at 8 months but the plane wouldn't start that day, so we figured it was a sign and scrubbed the trip.

Now, pregnant again (with twins this time), she's flying and wevegot plans for up to about 7 months again.
 
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I agree, 8 weeks is nothing. I'd try to go when conditions are favorable, early or later for the smooth ride.
 
Unless she has an issue her doc would have warned her about go ahead. I usually try to keep pregnant women at a density altitude below 9000' or give them supplemental O2.
 
Took my wife up for the first time at 5 months prego. The dr said it was ok as long as we stayed down low. We never went any higher than 4000MSL.
 
It is never safe to be around a pregnant woman. All them messed up hormones and such, she may want to harm you because she can't decide what she wants for lunch just as much as harm you while flying.

Best advice, avoid them.
 
Yea, if she is already pregnant you are not likely to get her pregnant again so safe as it is gonna get.:goofy:

Took my wife up when she was pregnant with our first kid no issues but would make sure she talked to her doctor.
 
CTLSi said:
8 weeks is nothing. a near term pregnancy is a little more trouble. but nothing about the flying affects pregnant women.
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Umm, no.

Pregnancy has increased risk of hypertension and DVT, both of which can be aggravated by flying. It's a question for the OB/GYN. They may not be factors for her.

And of course there is the nausea associated with early pregnancy….
 
Henning said:
Unless she has an issue her doc would have warned her about go ahead. I usually try to keep pregnant women at a density altitude below 9000' or give them supplemental O2.
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Why do you care what the DA is?

In your lungs, the temperature is always 98.6 F and the humidity is always 100%. People aren't air-cooled engines, and they react only to the pressure altitude.
 
I don't know the dynamics of the situation, but it sound like someone already beat you to the punch. Just sayin'.
 
MAKG1 said:
Why do you care what the DA is?

In your lungs, the temperature is always 98.6 F and the humidity is always 100%. People aren't air-cooled engines, and they react only to the pressure altitude.
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:dunno: Use whatever you want, my standard T/O brief calculation uses Density Altitude correction so I use that as the determining factor altitude for whatever. Since the difference, physiologically, between using PA and DA is as you point out, nothing, I am completely safe to use that number.
 
Henning said:
:dunno: Use whatever you want, my standard T/O brief calculation uses Density Altitude correction so I use that as the determining factor altitude for whatever. Since the difference, physiologically, between using PA and DA is as you point out, nothing, I am completely safe to use that number.
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It does make a difference, and it will be in the wrong direction on a cold day.

Humans don't feel DA because they are temperature regulated. They make the DA into PA. Breathing is controlled from inside, so you get the same amount of oxygen per breath at 10,000 pressure altitude when it's 90 deg or when it's -40.

Using DA is really important for your airplane. It's wrong for your passengers.
 
MAKG1 said:
It does make a difference, and it will be in the wrong direction on a cold day.

Humans don't feel DA because they are temperature regulated. They make the DA into PA. Breathing is controlled from inside, so you get the same amount of oxygen per breath at 10,000 pressure altitude when it's 90 deg or when it's -40.

Using DA is really important for your airplane. It's wrong for your passengers.
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I've never heard of a problem with too much oxygen until PPO2s get in the 1.6 range, though some people start into helium dilution at 1.3, but that's mostly for narcosis reasons, not CNS-O2 hits. Since that's not going to happen in an unpressurized airplane, not a factor. There is no plane I fly that will provide the endurance for the long term high level pulmonary O2 toxicity. So it goes back to the old O2 basic rule, "When in doubt and available, administer O2."

As for DA being incorrect on the bottom of the scale, you are correct, I neglected that factor as I don't fly in cold weather anymore, at least not high enough to make O2 an issue.:D Is true though, in cases of below standard it would cause a fault, but not one that would pass the brief uncorrected.
 
We flew on a long XC 2 months before my son's ETA. There was a little response noted when we arrived to the destination that concerned the both of us. It turned out benign.

The return trip happened to be a foray of unintentional VFR-IMC at night. Do not repeat my experience please, but no further reactions noted.

I couldn't recommend it beyond about 4-mos even with doctor approval, but this is just an anecdotal data point.
 
When my wife became pregnant, the Flight Surgeon attached to my squadron said she was OK to fly as PIC through the second trimester, but recommended against that in the third -- too much chance of something starting in flight and interfering with her ability to fly the plane. He also said that in the third trimester, we should stay within an hour of a hospital. Finally, he also recommended O2 above 10,000 PA.

So, as a passenger in a light plane in the first trimester, I'd say unless her OB has some objection, other than O2 above 19K, it's not a concern.
 
A friend of mine completed her IFR checkride about a week before her baby was born but she did have Dr. approval.

I wouldn't worry so much about low altitude GA flying, I'd worry more about the mood swings in such a confined space..... don't tell my wife I typed this.... ;)
 
Henning said:
Since the difference, physiologically, between using PA and DA is as you point out, nothing,...
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Except it isn't nothing. PA, and only PA, is the determining factor for the need for supplemental O2 in an unpressurized aircraft. If you are at a PA where you don't need O2, you can run the temp up as high as you like and it won't change your need for supplemental O2 even though the DA runs way up. Likewise, if the PA is high enough to require it, cooling the air to lower DA won't obviate that need. Ask any aviation physiologist or see any FAA reference.
 
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I had an instrument student who flew her 182 over the Cascades when she was eight months pregnant....with her doc's approval, I assume.

Bob Gardner
 
bobmrg said:
I had an instrument student who flew her 182 over the Cascades when she was eight months pregnant....with her doc's approval, I assume.

Bob Gardner
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I'd imagine it's rather difficult to flare with a basketball on your lap.
 
Pull the seat to the rear during the approach phase (not that I would - I sit closer to the panel during T/O & L).
 
Ron Levy said:
Except it isn't nothing. PA, and only PA, is the determining factor for the need for supplemental O2 in an unpressurized aircraft. If you are at a PA where you don't need O2, you can run the temp up as high as you like and it won't change your need for supplemental O2 even though the DA runs way up. Likewise, if the PA is high enough to require it, cooling the air to lower DA won't obviate that need. Ask any aviation physiologist or see any FAA reference.
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So can anyone tell me WHY this is? The air you breathe cannot change temperature instantly, so while cold air will be warmed (and hot air cooled) when you inhale, I don't buy the "everything's 98.6" thing. Since our lungs are a relatively fixed maximum volume, it would seem that temperature would have an effect.

Also, when I go running or otherwise exert myself physically on the ground, it's MUCH more difficult for me to breathe when it's hot and humid out than when it's cool and dry out. When it's hot I feel like I can't get enough air for a while, and it's best solved by going into a cool air-conditioned building. If DA doesn't affect us, why does this happen?
 
Why we're at it let's talk about epidural options, pintocin, and the 5 centimeters.
 
Ryanb said:
Someone i know that is pregnant is interested in going for a local ride, shes about 8 weeks along, is it safe to have her fly?
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Would she be concerned about flying commercial at 8 weeks?
 
flyingcheesehead said:
So can anyone tell me WHY this is? The air you breathe cannot change temperature instantly, so while cold air will be warmed (and hot air cooled) when you inhale, I don't buy the "everything's 98.6" thing. Since our lungs are a relatively fixed maximum volume, it would seem that temperature would have an effect.

Also, when I go running or otherwise exert myself physically on the ground, it's MUCH more difficult for me to breathe when it's hot and humid out than when it's cool and dry out. When it's hot I feel like I can't get enough air for a while, and it's best solved by going into a cool air-conditioned building. If DA doesn't affect us, why does this happen?
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In a nutshell, the specific heat of all the fluids in and around your lungs is orders of magnitude larger than the specific heat of the air. In extreme cold, unprotected, you can indeed breathe in less than 98.6 air. It hurts. You'll know it.

I guess you haven't been hypoxic. You don't feel like you "aren't getting enough air." You feel fine. You just start behaving strangely, and your judgment and motor skills go to hell, not all that different from being drunk.
 
flyingcheesehead said:
The air you breathe cannot change temperature instantly, so while cold air will be warmed (and hot air cooled) when you inhale, I don't buy the "everything's 98.6" thing.
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As MAKG said, in fact the air you breathe is changing temperature pretty instantly, and except for really extreme situations, the wet warmth of your nose, mouth, airways, lungs overwhelms the relatively low specific heat of the air entering your lungs.

During normal nose breathing, air is heated to about 97F and has an 80-90% relative humidity by the time it reaches the carina (that bit where your trachea splits into bronchi to go to your lungs separately). Things go a bit slower than that if you're breathing through your mouth, but by the time air gets to the alveoli (the air sacs in your lungs that actually do gas exchange with blood), it's safe to assume in all but the weirdest situations (antarctic explorers or mountain climbers caught out) that the air is body-temperature and fully saturated.

So, for normal breathing purposes, it doesn't matter if the humidity and warmth is in the air already or added to the air by your body on the way in.

flyingcheesehead said:
Also, when I go running or otherwise exert myself physically on the ground, it's MUCH more difficult for me to breathe when it's hot and humid out than when it's cool and dry out. When it's hot I feel like I can't get enough air for a while, and it's best solved by going into a cool air-conditioned building. If DA doesn't affect us, why does this happen?
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Exercise is definitely more difficult in heat and humidity. That's because your body relies on the fact that it's dumping heat and water into the air you're breathing in order to cool down. (We may not be dogs, but we still use panting for cooling to some degree.) If the air coming in is already hot and humid, the body isn't pumping that heat and evaporative air into the air for exhalation, and so there is more heat strain on the body overall. Part of the response (though a smallish part) is to try to breathe more (and therefore feel like you can't get enough air) in order to get that cooling going.

A bigger part of the response is that (unlike dogs) we do most of our physiologic cooling through our skin: by sweating and dilating the capillaries in our skin. (If we make our skin warm, that heat is lost by conduction, convection, radiation, and sweat evaporation.) The dilation of capillaries all over the skin drops the resistance to bloodflow in the overall body system, and means your heart needs to pump all the harder to maintain pressure on the system.*

This effect -- and the resultant workload on the heart -- is higher in hot and humid environments as conductive/convective heat loss is less (heat) and evaporative loss from sweat is less effective (humidity). That cardiac load feels very much like air hunger and "can't quite catch my breath" and "can't go any harder, but it's not because of my legs".

For healthy people, the "not getting enough air" feeling is generally from having too much CO2, not too little O2. That's why, as MAKG said, you don't generally feel hypoxia as air hunger. (This isn't always true. For example, many people with advanced COPD have lost their CO2 sense and instead their drive to breathe is in fact governed by hypoxia.)


* If you're more an electronics person, the heart is a approximately constant-voltage generator. When resistance in the skin drops -- which is in parallel with the rest of the body "load" -- the heart has to ramp up the current in order to maintain the same voltage and thereby keep the other bits of the body running appropriately. Except the problem is even worse, because exercising muscles also become low-resistance loads, and exercise encourages the body to increase voltage (blood pressure) rather than just maintaining it.
 
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flyingcheesehead said:
The air you breathe cannot change temperature instantly, so while cold air will be warmed (and hot air cooled) when you inhale, I don't buy the "everything's 98.6" thing.
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The question of how fast air warms in your lungs is not the sort of thing you can evaluate by asking yourself whether you feel like "buying" it. It's the sort of question that's well within the scope of scientific knowledge, so you have to look up the known answer (and, if you're skeptical, find out how that answer was arrived at).

Also, when I go running or otherwise exert myself physically on the ground, it's MUCH more difficult for me to breathe when it's hot and humid out than when it's cool and dry out. When it's hot I feel like I can't get enough air for a while, and it's best solved by going into a cool air-conditioned building. If DA doesn't affect us, why does this happen?
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If you exercise when it's hot and humid, your body has trouble shedding the heat your muscles generate. So your body temperature rises, which is what you're reacting to. It has nothing to do with air density, which may be either higher or lower than average on a hot, humid day.
 
MAKG1 said:
In a nutshell, the specific heat of all the fluids in and around your lungs is orders of magnitude larger than the specific heat of the air.
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Isn't it also the case that even if the temperatures are unequal, a substance's diffusion across a membrane depends only on its partial pressure on each side of the membrane, rather than on the substance's density?
 
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I laughed my way through this thread until I feared I would wet myself.
Thanks guys - I was kinda feeling down this morning until I hit on this one.

dr. o
btw, I recommend Guyton's Textbook Of Medical Physiology for bedtime reading.
 
acrophile said:
Isn't it also the case that even if the temperatures are unequal, a substance's diffusion across a membrane depends only on its partial pressure on each side of the membrane, rather than on the substance's density?
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Yes, but absolute partial pressure rather than relative partial pressure. If gas were exchanged directly between atmospheric air and blood, the partial pressure of oxygen would depend a bit on atmospheric conditions, e.g.:

Record highs in air pressure are about 32 inHg. (Altimeter setting 32.00; never heard that I bet!) In completely dry air at that pressure, the partial pressure of oxygen is 6.7 inHg.

Record lows are in the neighborhood of 26 inHg. Granted, these are generally in the midst of hurricanes, and we aren't flying, but let's put that pressure on a hot, wet day. The vapor pressure of water at 100F is about 2 inHg, so the (everything-except-water) partial pressure is 24 inHg, and the partial pressure of oxygen is 5 inHg, or the equivalent of 6,000 feet altitude in a standard atmosphere.

And if your reply is "but most of that is due to the absolute air pressure," you're right. A more fair comparison is probably to use a more realistic air pressure -- 30 inHg. On a dry day, that's a partial pressure of oxygen of 6.28 inHg. On a wet day at 35F, that's 6.24 inHg. On a wet day at 100F, that's 5.87 inHg, or about 1,800 ft pressure altitude -- much less an issue.


But of course all that is moot. Because we have big wet airways and lungs, as far as our blood is concerned, we're (almost) always breathing wet, warm air.
 
MAKG1 said:
In a nutshell, the specific heat of all the fluids in and around your lungs is orders of magnitude larger than the specific heat of the air. In extreme cold, unprotected, you can indeed breathe in less than 98.6 air. It hurts. You'll know it.
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That's the kind of thing I was thinking about - In midwinter you can feel it (and for me, at least, it makes me cough a lot). But I figure it's gotta be pretty significantly different from 98.6 before you can feel it - If the air was, say 88.6 in your lungs would you really feel it?

I guess you haven't been hypoxic. You don't feel like you "aren't getting enough air." You feel fine. You just start behaving strangely, and your judgment and motor skills go to hell, not all that different from being drunk.
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I've only been there to the extent that I can feel my heart beating harder... Which is gonna happen with strenuous exercise anyway.
 
mcmanigle said:
--snip--
And if your reply is "but most of that is due to the absolute air pressure," you're right. A more fair comparison is probably to use a more realistic air pressure -- 30 inHg. On a dry day, that's a partial pressure of oxygen of 6.28 inHg. On a wet day at 35F, that's 6.24 inHg. On a wet day at 100F, that's 5.87 inHg, or about 1,800 ft pressure altitude -- much less an issue.
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Very interesting... Thanks!
 
acrophile said:
The question of how fast air warms in your lungs is not the sort of thing you can evaluate by asking yourself whether you feel like "buying" it. It's the sort of question that's well within the scope of scientific knowledge, so you have to look up the known answer (and, if you're skeptical, find out how that answer was arrived at).
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I say that based on my engineering knowledge, mainly thermodynamics and heat transfer, not just a hunch - It doesn't make sense to me, and I'm trying to make sense of it by asking these questions. Believe me, I'm all about science, I just like to know the "why" and "how" behind it all.

If you exercise when it's hot and humid, your body has trouble shedding the heat your muscles generate. So your body temperature rises, which is what you're reacting to. It has nothing to do with air density, which may be either higher or lower than average on a hot, humid day.
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Air density is affected by temperature, thus on a hot, humid day the air's density will be lower than normal. I think what you meant to say in that last sentence is pressure, not density, can be higher or lower than average. Temperature is the largest factor in density.

Body temperature won't rise much - Only a few degrees F warmer and you're going to be in a world of hurt - so I don't think the body's extra heat would be contributing much to the air density inside your lungs.
 
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