Why don't babies which are head-downwards for months have all the blood rushing to their heads?

[Wigeon]

Can someone scientific / medical enlighten me? Unborn babies spend weeks and weeks head down, with no apparent ill effects. If I stood on my head for weeks, I would feel terrible and get very red in the face. I'm sure there's a perfectly sensible medical / scientific reason why babies don't - please tell me what it is! It's been bothering me for a while .

So pleased to read this thread! This is one of those questions I always wanted to ask, but always felt too embarrassed...

Posypom - I have no intention of dangling my (as yet unborn) newborn on its head for hours on end to see if the blood rushes to its head , don't worry - what I mean is: why is it ok for a fetus to spend many weeks upside down, but (very presumably) not for a newborn, if the "fetuses have fast heart rates which stops the blood rushing to their heads" is the correct theory for why it's ok for fetuses to be upside-down. Because newborns also have fast heart rates. So it can't just be that. And it can't just be the fact that fetuses have spent their first and second trimesters flipping upside down and right way up, because many of them spend all the weeks of the third trimester upside down!

Gah! I feel I am no closer to The Truth!

Hmm, I suppose if you 'dangle' them upside down it is different they are all stretched out with legs higher up in relation to the head, rather than in curled up feotal position.... Not suggesting anyone try this out though!

Would the fact that there's so much less blood in a baby's body be a factor too (know I'm joining late, sorry but the thread intrigued me!)? Heart needs to work less hard to shift it round. Also there's less distance between the heart and the head when they're that small.

Not sure how/if this would make a difference but it's what jumped into my mind!

There are differences between the state of the baby in the womb and then after it's born. In the womb for example the lungs aren't inflated - they don't expand till baby comes out and breathes. (I love that - the perfectness of that - the lungs are ready but it dosn't need them yet so they just stay folded up) The baby is all folded up too. If you did that to a newborn it would be very, very unhappy! I guess the blood to the head thing is another difference.

Oh no, of course I didn't think anyone would actually do this, all I meant was are we sure that holding very carefully and lovingly a newborn upside down would damage them? Please don't think I'm suggesting anyone does this!!! But I doubt there's any proof that this would hurt a newborn as no one would dare test the theory. Therefore we can't assume that just because it hurts an adult it would also hurt a newborn.

So... before anyone can answer your question of "why doesn't this hurt a newborn" we must first ascertain whether or not it would hurt a newborn. If it wouldn't hurt a newborn (which it may not - we can't assume it does as it obviously doesn't hurt a foetus) then your question is moot.

Loving this thread!!

My DP was reading this and said 'kids love hanging upsidedown for hours' - apparently he personally spent many an hour hanging by his knees from a bannister and loved it, so maybe it isn't as bad for littl'uns?

Or maybe he's just weird!

This is such an interesting and intriguing question. I have no idea what the answer could be - but it's got me thinking. Could it be that a foetus's circulation system is somewhat different because the umbilical cord and placenta is part of that and could act as a regulatory mechanism? I mean in the sense that the volume of blood that's pumped to the head could vary depending on need? I was thinking about the system involved in the giraffe, where blood is normally pumped up that long neck but then not so much when they're drinking from a water-hole otherwise they'd fall over.

I may be wrong, northernlurker, (which wouldn't surprise me at all as it isn't unusual ), but I thought that the lungs were partially inflated but with amniotic fluid. Which is a bit squicky as foetuses also pee into the amniotic fluid in later pregnancy.

FirstVix's comment prompted me to think of bats. Adult bats spend hours upside-down, so presumably they have a mechanism to prevent blood rushing to their heads.

I bet David Attenborough could provide an answer.

posypom

I am at very late stages of labour and think the baby is engaged. This happened with my first DS and it feels - at 36 weeks - as though the head is really stuck in my groin. I think it was like this with DS for a few weeks before giving birth.

DS has mild cerebral palsy and I have always worried that because he was head down but not cushioned by water (as he was engaged, I suppose) his head might have been banging on a hard surface, upside down and this might have caused the CP.

I did then and do now a lot of walking.

Thank you.

Love the bat / giraffe comparison. Also good point about the possibility of hanging a newborn upside down not necessarily being bad for it (albeit difficult to prove), and therefore the fast heart beat theory might hold water.

Hmmm. Still no nearer a definitive answer!

Skewiff - I hope you aren't actually in the very late stages of labour or you should be concentrating on pushing, not posting on this thread!!

a baby's blood doesn't 'rush to the head' in the same way that our blood doesn't all pool in our feet.

we get a head rush because we adapt to being upright.. a baby hasn't done that yet and is in all positions in the womb... i suspect that holding a newborn upside down would be totatlly ok too as long as you support the neck - but i'm not willing to try it.

Fluffles - I thought our blood doesn't rush to our feet because we have one-way valves in our veins - heart pumps blood out to the extremities and it gets pushed back again passively but the valves stop it flowing back?

It's not that we adapt to being upright it is that we are adapted by evolution to be uprigh creatures. I guess babies in the uturus are adapted to be anyway up, but I still wonder how?

we do have one-way valves in our heart but they stop the blood gushing back into the empty heart chambers - they do not differentiate between blood going to your shoulders, neck and head and blood going down to your feet. veins going 'up' to your head have the same valves and veins that go 'down' to your feet.
muscle movement helps the blood back to the heart from both directions.

I asked a Dr friend this once and he said they weren't really sure! But that it was thought to be partly acclimatisation (sp?) and partly due to the not needing to breathe yet. He said it could be that the umbilical cord acts like a self righting balance.

Fluffles - no, there are mini valves in your veins to stop the blood pooling at your feet en.m.wikipedia.org/wiki/Vein.

Himalaya but the veins going down your legs and going up into your shoulders, neck and head have the same valves - so it can't be about which way up you are, either way the valves send the blood back to your heart - not specifically 'up'.

Medic friend of mine adds:

"I think the sensation we get of 'blood to the head' is because of a feeling of pressure in blood vessels. Arteries are elastic, and hence why they have a role in controlling blood pressure, but they have to regulate differently for brain, lungs, limbs etc. I expect that foetal blood vessels adapt over the period to appropriately control blood flow through them. We don't constantly have an uncomfortable feeling of 'blood to the feet' for example!!"

I guess it is basically that the foetal circulation system is adapted for life in the womb. Never mind the upside down bit, we would be pretty uncomfortable crunched up and imobile like that for so long.

my boyfriend of 12 months just told me to he doesn’t want to be with me when I give birth to his twins, he said he gets bored waiting and would rather play Xbox, I said I’d like support and he said to call my friends, is this reasonable????