Baby breathing in womb.
July 26, 2023 5:51 PM Subscribe
How does an unborn baby breath or get oxygen in the womb?
The mother's oxygen rich blood crosses through the placenta and then travels via the umbilical cord which links it to the baby's bloodstream. Here's more from the Cleveland Clinic.
posted by metahawk at 5:54 PM on July 26, 2023 [3 favorites]
posted by metahawk at 5:54 PM on July 26, 2023 [3 favorites]
Through the mother, via oxygenated blood delivered via the placenta and umbilical cord. In utero, the lungs of the fetus are full of amniotic fluid, and thus aren't involved in breathing.
posted by griffey at 5:55 PM on July 26, 2023 [1 favorite]
posted by griffey at 5:55 PM on July 26, 2023 [1 favorite]
(Note, the umbilical cord and the placenta and the amniotic sac are all "part of" the baby. The mother's blood does not enter the umbilical cord.)
posted by heatherlogan at 5:56 PM on July 26, 2023 [6 favorites]
posted by heatherlogan at 5:56 PM on July 26, 2023 [6 favorites]
The same way your heart and liver get oxygen, via your blood. A fetus is essentially an organ in the pregnant person's body.
posted by shadygrove at 5:57 PM on July 26, 2023 [13 favorites]
posted by shadygrove at 5:57 PM on July 26, 2023 [13 favorites]
And just as a note when they say babies die or suffer hypoxia due to the “cord around the neck” it’s not because they are strangled - they aren’t using their lungs yet - it’s because the cord is pinched so the baby doesn’t receive enough oxygen-rich blood via the umbilical cord.
The process by which babies go from “breathing” amniotic fluid to breathing air in a very short time is really super awesome too.
And finally, in order to get enough oxygen in the womb, fetal hemoglobin is different from adult.
If you really want to blow your mind, check out bilirubin, jaundice, and cerebral palsy. When baby livers can’t process old red blood cells effectively, bilirubin builds up and can cause brain damage. (That processing happens via the umbilical cord before birth.)
Babies really are little bundles of “everything going right.”
posted by warriorqueen at 6:16 PM on July 26, 2023 [17 favorites]
The process by which babies go from “breathing” amniotic fluid to breathing air in a very short time is really super awesome too.
And finally, in order to get enough oxygen in the womb, fetal hemoglobin is different from adult.
If you really want to blow your mind, check out bilirubin, jaundice, and cerebral palsy. When baby livers can’t process old red blood cells effectively, bilirubin builds up and can cause brain damage. (That processing happens via the umbilical cord before birth.)
Babies really are little bundles of “everything going right.”
posted by warriorqueen at 6:16 PM on July 26, 2023 [17 favorites]
Not to hijack, I hope, but while I understand that's how it works in (most) mammals and other animals that give live birth, I hope someone might expand upon the answers already given to say more about how it works with egg-laying species.
posted by Nerd of the North at 8:14 PM on July 26, 2023 [1 favorite]
posted by Nerd of the North at 8:14 PM on July 26, 2023 [1 favorite]
The shell is not impermeable to air. It has pores that let the air in. The chick inside the shell has something called the allantois which is a membrane bag attached to the chick's gut at one end and the membrane that lines the shell at the other. The fused part of the allantois and the chorion (membrane that lines the shell) has tiny blood vessels in it, like the tiny blood vessels in young lungs that allow oxygen to enter your bloodstream.
So if you were to put an egg into water the chick inside would die. And that is why if you want to preserve an egg without refrigeration you do so by waterproofing it - dipping it in oil, or wax to seal the pores in the shell.
posted by Jane the Brown at 8:26 PM on July 26, 2023 [6 favorites]
So if you were to put an egg into water the chick inside would die. And that is why if you want to preserve an egg without refrigeration you do so by waterproofing it - dipping it in oil, or wax to seal the pores in the shell.
posted by Jane the Brown at 8:26 PM on July 26, 2023 [6 favorites]
A couple of notes:
The baby doesn't breathe amniotic fluid, and its lungs aren't expanded, so they really can't be said to be full of anything. Babies do swallow a certain amount of it.
One of the things that professionals don't like to tell expectant mothers is that amniotic fluid is almost entirely urine, produced by the baby's kidneys.
Amniotic fluid is contained, with the baby, in the amniotic sac. Since there's no way bacteria can get in there it has to be sterile. That's so obvious that nobody ever checked, and when someone did, just a few years ago, it turned out not to be sterile at all.
There's a lot of stuff like this in biology and medicine. In the 920s the number of human chromosomes was 48. Thirty years of researchers and students looked at pictures of chromosomes and they all saw that was right. In 1956 someone (Tjio and Levan) counted them and found there were 46.
Passage through the birth canal squeezes the baby tightly enough to compress its respiratory tract and remove any fluid from its mouth and trachea. It also inoculates the baby's skin with desirable bacteria from its mother, which is why, while c-section babies look more healthy and have better apgars, vaginal birth is preferable.
As mentioned above, the baby's blood does not mingle with the mother's. However, at the moment of birth there is some exchange, which is why an Rh- mother may produce antibodies to her Rh+ baby which will attempt to kill it shortly after it's born. One of the great things about modern medicine is that we can easily deal with that.
I've had several people tell me that when you know all the details pregnancy and birth aren't so beautiful, but they still are.
posted by AugustusCrunch at 12:34 AM on July 27, 2023 [6 favorites]
The baby doesn't breathe amniotic fluid, and its lungs aren't expanded, so they really can't be said to be full of anything. Babies do swallow a certain amount of it.
One of the things that professionals don't like to tell expectant mothers is that amniotic fluid is almost entirely urine, produced by the baby's kidneys.
Amniotic fluid is contained, with the baby, in the amniotic sac. Since there's no way bacteria can get in there it has to be sterile. That's so obvious that nobody ever checked, and when someone did, just a few years ago, it turned out not to be sterile at all.
There's a lot of stuff like this in biology and medicine. In the 920s the number of human chromosomes was 48. Thirty years of researchers and students looked at pictures of chromosomes and they all saw that was right. In 1956 someone (Tjio and Levan) counted them and found there were 46.
Passage through the birth canal squeezes the baby tightly enough to compress its respiratory tract and remove any fluid from its mouth and trachea. It also inoculates the baby's skin with desirable bacteria from its mother, which is why, while c-section babies look more healthy and have better apgars, vaginal birth is preferable.
As mentioned above, the baby's blood does not mingle with the mother's. However, at the moment of birth there is some exchange, which is why an Rh- mother may produce antibodies to her Rh+ baby which will attempt to kill it shortly after it's born. One of the great things about modern medicine is that we can easily deal with that.
I've had several people tell me that when you know all the details pregnancy and birth aren't so beautiful, but they still are.
posted by AugustusCrunch at 12:34 AM on July 27, 2023 [6 favorites]
Should also mention [TMI alert] the two miraculous switcheroos that occur at birth time. in utero the blood is diverted away from the uninflated lungs by two mechanisms a) the foramen ovale (the oval 'ole) between the right and left atria of the heart. This allows blood to miss the right ventricle > pulmonary artery > lungs and have another go round the fetal body. b) the back-stop is the ductus arteriosus a tube which connects the pulmonary artery with the aorta and also shunts lung-bound blood back into the body circulation. Obvs these two channels are imperfect: some oxygenated blood reaches the fetal lungs so they can grow and develop.
At birth both these channels block up with quite precise timing (there's a lot going on) initially by contraction and later by tissue remodelling. If you look/feel carefully at the wall between the atria of a post-natal heart you can find the fossa ovale (the oval dent) where the wall is a little thinner. In 25% of us the foramen ovale remains open "patent" and these people go through life not a bother on them until a cardiologist starts to investigate for other reasons. Patent ductus arteriosus PDA is another defect which causes too high BP in the lungs. It can be closed off surgically or medically with NSAIDs. PDA is much more common ~50% in kids who have contracted measles in utero.
Hole in the heart babies / surgery is usually in the wall between the ventricles.
posted by BobTheScientist at 1:24 AM on July 27, 2023 [3 favorites]
At birth both these channels block up with quite precise timing (there's a lot going on) initially by contraction and later by tissue remodelling. If you look/feel carefully at the wall between the atria of a post-natal heart you can find the fossa ovale (the oval dent) where the wall is a little thinner. In 25% of us the foramen ovale remains open "patent" and these people go through life not a bother on them until a cardiologist starts to investigate for other reasons. Patent ductus arteriosus PDA is another defect which causes too high BP in the lungs. It can be closed off surgically or medically with NSAIDs. PDA is much more common ~50% in kids who have contracted measles in utero.
Hole in the heart babies / surgery is usually in the wall between the ventricles.
posted by BobTheScientist at 1:24 AM on July 27, 2023 [3 favorites]
A fetus is essentially an organ in the pregnant person's body. That never occurred to me and it's an excellent point of view.
posted by theora55 at 7:14 AM on July 27, 2023 [2 favorites]
posted by theora55 at 7:14 AM on July 27, 2023 [2 favorites]
c-section babies look more healthy and have better apgars
Link please? This is not consistent with my experience as an L&D nurse.
posted by jesourie at 10:40 AM on July 28, 2023
Link please? This is not consistent with my experience as an L&D nurse.
posted by jesourie at 10:40 AM on July 28, 2023
« Older Keeping cookies fresh - best course of action? | Questions about Sinead O'Connor's "Silent Night"... Newer »
This thread is closed to new comments.
posted by heatherlogan at 5:53 PM on July 26, 2023 [4 favorites]