# Baby's first breath, how? **URL:** \ **Category:** Factual Questions\ **Created:** [January 6, 2014, 7:54pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055 "2014-01-06T19:54:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![twhitt](https://avatars.discourse-cdn.com/v4/letter/t/87869e/32.png) [@twhitt](https://boards.straightdope.com/u/twhitt)\ **Post date:** [January 6, 2014, 7:54pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/1 "2014-01-06T19:54:06Z")
When a fetus is in amniotic fluid, it mimics breathing motions without gas exchange happening in the lungs. So the fetus’s lungs are filled with amniotic fluid, no problem I guess. Except if an adult’s lungs are filled with fluid, even a relatively benign fluid, it’s tremendously difficult to clear them to allow normal breathing. That would be a medical emergency, and yet newborns have (relatively) no trouble taking that first breath. Obviously this works out fine in most cases, but I’m failing to see the mechanism that clears the newborn infant’s lungs of fluid to allow for air to flow. I could imagine a few scenarios that all seem unlikely. Don’t shake the baby and all that. I guess I didn’t phrase that as a question. How is it that a newborn’s lungs empty themselves of liquid to a sufficient degree to allow for them to begin normal respiration? ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [January 6, 2014, 7:59pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/2 "2014-01-06T19:59:14Z")
This is an interesting article about the process [Changes in the newborn at birth: MedlinePlus Medical Encyclopedia](http://www.nlm.nih.gov/medlineplus/ency/article/002395.htm) ---
**Author:** ![twhitt](https://avatars.discourse-cdn.com/v4/letter/t/87869e/32.png) [@twhitt](https://boards.straightdope.com/u/twhitt)\ **Post date:** [January 6, 2014, 8:02pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/3 "2014-01-06T20:02:35Z")
> [@elfkin477](#): > > This is an interesting article about the process [Changes in the newborn at birth: MedlinePlus Medical Encyclopedia](http://www.nlm.nih.gov/medlineplus/ency/article/002395.htm) Thanks! I already did a google search, finding that one and a few others. It really only says that it happens, though, which is obvious enough from the evidence. How? ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 6, 2014, 8:15pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/4 "2014-01-06T20:15:10Z")
My recollection is that it’s generally squeezed out by vaginal birth. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 6, 2014, 8:21pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/5 "2014-01-06T20:21:33Z")
Found this: > [@](#): > > During pregnancy, a baby’s lungs are filled with fluid. Chemical signals just before birth will start to clear the fluid out of the lung. Then physical pressures during labor and birth will push more fluid out. After birth, the baby may also cough some of the fluid out of the lungs. The baby’s first breaths should clear out any remaining fluid. [http://www.med.nyu.edu/content?ChunkIID=102753](http://www.med.nyu.edu/content?ChunkIID=102753) ---
**Author:** ![zoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zoid/32/336_2.png) [@zoid](https://boards.straightdope.com/u/zoid)\ **Post date:** [January 6, 2014, 8:24pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/6 "2014-01-06T20:24:31Z")
When my twins were born via C-section the doc used a sucker [kind of like this](http://www.target.com/p/safety-1st-newborn-nasal-aspirator-pink/-/A-14061596?ref=tgt_adv_XSG10001&AFID=Google_PLA_df&LNM=%7C14061596&CPNG=Health+Beauty&kpid=14061596&LID=PA&ci_src=17588969&ci_sku=14061596&gclid=CJnVrKKw6rsCFbQWMgod0D8AFg)but bigger to get the fluid out of their mouths and noses. A few pulls with one of those thing and the kids reacted pretty strongly, coughing and spitting, and I suspect finished the job on their own ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [January 6, 2014, 8:29pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/7 "2014-01-06T20:29:02Z")
Since all placental mammals face this situation, it’s nice to know we’ve had at least 100M years of evolution to work the kinks out of this issue. Otherwise… oops! ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [January 6, 2014, 8:29pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/8 "2014-01-06T20:29:38Z")
> [@twhitt](#): > > When a fetus is in amniotic fluid, it mimics breathing motions without gas exchange happening in the lungs. So the fetus’s lungs are filled with amniotic fluid, no problem I guess. Except if an adult’s lungs are filled with fluid, even a relatively benign fluid, it’s tremendously difficult to clear them to allow normal breathing. That would be a medical emergency, and yet newborns have (relatively) no trouble taking that first breath. Obviously this works out fine in most cases, but I’m failing to see the mechanism that clears the newborn infant’s lungs of fluid to allow for air to flow. I could imagine a few scenarios that all seem unlikely. Don’t shake the baby and all that. > > I guess I didn’t phrase that as a question. How is it that a newborn’s lungs empty themselves of liquid to a sufficient degree to allow for them to begin normal respiration? This appears to indicate there isn’t much fluid in the lungs to begin with: > [@](#): > > Terminal saccular period - week 26 to birth - The important blood-air barrier is established during the terminal saccular period. Specialized cells of the respiratory epithelium appear at this time, including type I alveolar cells across which gas exchange occurs, and type II alveolar cells which secrete pulmonary surfactant. This surfactant is important in reducing the surface tension at the air-alveolar surface, allowing expansion of the terminal saccules. _During this time, the lungs are rock-like and will sink if placed in water but will expand after the first breath, a trait which is used to determine if babies were born alive._ > **[Lung](https://en.wikipedia.org/wiki/Development_of_human_lung)** > > The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream, and to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. Respiration is driven by different muscular systems in different species. Ma... ---
**Author:** ![twhitt](https://avatars.discourse-cdn.com/v4/letter/t/87869e/32.png) [@twhitt](https://boards.straightdope.com/u/twhitt)\ **Post date:** [January 6, 2014, 9:24pm UTC](https://boards.straightdope.com/t/babys-first-breath-how/678055/9 "2014-01-06T21:24:07Z")
> [@John\_Mace](#): > > Since all placental mammals face this situation, it’s nice to know we’ve had at least 100M years of evolution to work the kinks out of this issue. Otherwise… oops! True, of course. But really, all air-breathing vertebrates have this issue; I was just imagining that the difficulty involved was one of air volume. It’s not hard to imagine that a newborn chick would have little difficulty initially pulling open the lungs against the stresses involved, but an elephant should have it much worse than we do. And my goodness, whales.