Is extending human gestation realistic or I should stick with 9 months?

Question

I'm developing a world in the near future where a start-up company develops an artificial womb. Now well-off people could grow their children from their eggs & sperm. My story is about couples that can't conceive and serve as test subjects of the program.

Since I read that human babies are born prematurely is it realistic to extend the gestation period to 21 months thus having a more developed baby? My setting works better if the 99% feel that technology allows the wealthy to order their children, while the not so lucky women risk their health or have gaps in their careers.

Explanation:

The setting is near future, something like the next year or two. The company barely managed to mimic what mother nature is doing, and is still very vulnerable to proving that their technology results in healthy normal babies. I assume that no giant breakthrough in genetic engineering occurred that will enable us to create designer babies.

Answer 1

To pile onto what @kingledion said, going more than 9 months is actually dangerous. Most doctors will demand a woman get induced if the baby's not coming by two weeks late, because anything beyond that significantly increases the chances of still birth.

Other than that, while 1-year-olds aren't exactly geniuses, a 1-year-old who's been learning outside the womb is going to be crawling/walking, gesturing, grabbing, babbling, and will know many words that they hear. A 1-year-old who's just been born is going to be way behind developmentally, and may never be able to catch up.

Additionally, visual development is highly dependent on actually being able to see. This is one of the reasons why doctors will try and correct visual problems (cataracts, squints, etc.) as soon as possible, even if it requires somewhat dangerous surgery. "Ah," you say, "my womb will let them see out." The problem with this is, even if they can see, they need things to look at. And even if they have things to look at, they need to be able to interact with those things for the proper neural connections to form. How do we know this? Experimental studies involving sewing kittens' eyes shut, keeping them in a box for several months with only vertical stripes, and controlling whether they can move or not.

Answer 2

While you are correct that humans are born a bit early in their development (compared to animals like deer that can get up and run within hours of birth), simply leaving a fetus in an artificial womb would have issues. Post-term fetuses increasing in size run the risk of out growing the placenta (it drastically slows growing around 37 weeks or so), defecating in their own amnionic fluid and inhaling it (known as meconium aspiration syndrome), wrapping themselves in their umbilical cord as they become more active, and potentially out growing the fetal circulation pathways necessary to bypass the lungs. The foramen ovale and ductus arteriosus may not be sufficient to supply blood for a large fetus. Although massive infants of 20+ pounds have been born, those infants may suffer from significant health issues later in life, usually because the mother had gestational diabetes.

A longer gestational period may help somewhat with infant muscle tone, motor coordination, and digestion, but there will be the risk of losing protective reflexes (mainly related to swallowing/breathing) before the baby learns the proper techniques in order to feed safely. A few more weeks in the artificial womb probably wouldn't be an issue and could lead to a baby a bit larger, more capable of sleeping through the night and feeding more at a time, but of course if it ISN'T feeding in utero it won't be able to develop these capabilities.

Alas, simply letting a fetus hang out in the womb for a few more months won't get you the equivalent of a 3 month infant. They won't have the same feeding capacity, lung volume, muscle tone, visual/auditory acuity, etc. Perhaps if they were kept suspended in fluid in a clear womb where they could see outside and had lots of room to move around they might have some of this early development but ultimately I don't think there would be much benefit versus the risks for placental insufficiency, meconium aspiration, and having a big baby that doesn't have a stomach size and feeding skills to match.

Answer 3

Stick with 9 months, given this is real-world humans. The limiting factor is that the baby's head has to fit through the mother's pelvic girdle, which is a ring of bone. At the current nine-month human gestation, this is almost always possible, but the safety margin isn't huge.

Babies who are born late continue to grow and can readily become too large to fit, which requires an emergency Caesarean operation. This is not something that you want to make standard practice.

Answer 4

No it is not realistic, the shape of a baby is like that because it grows inside uterus: if you keep him more time than needed in a restricted space he could grow deformed or with some malformed organs, the human body works by staying about 9 months in uterus and then by staying a like on "the ground". Bones grow in response to gravity, if you grow in something like "floating fluid" the body will grow in a different manner that could cause at least social problems and eventually health problems.

Also mother attentions are necessary for correct mental grow, all cares are important to a baby.

Answer 5

Evolution favoured nine month because a newborn that was significantly larger and further developed would be stuck inside, because it's mother belongs to a species that has evolved into walking upright etc. No problem for you.

But: Human newborns are not exactly underdeveloped, or only if you compare them to, say, horses or giraffes. It's true for the bone structure, they are pretty small, for the reason given above. Otherwise they are rather overdeveloped for their age. Respiratory, immune, digestive system, all working (more or less). It would surely be possible to adapt a lot of this, because it all happens in close interaction with the mother's body. Question is how, and how high the price would be to find out.

An then some parts might even demand some genetic engineering. In which case they'd arguably be no longer human. ;-)

Answer 6

Because homo sapiens sapiens had a gestation period of 9 month for milleniums, everything (brain, muscle,immunie system, digestive system) is calibrated to start working properly around 9 month. Any shorter or longer gestation would cause more problems than it solves UNLESS you modify our DNA. However the OP ruled that out so I think the benefits of >9 month gestation if there are any are dwarfed by all the complications it ll cause.

Answer 7

the limit of 9 months is generally due to head-to-pelvis ratio. escaping that trap implies that these children could develop larger heads (and larger brains). the obvious advantages are either increased intelligence or larger overall size.

that said, if you have the technology to increase brain size while growing an embryo into a fetus, you probably also have the technology to increase brain size after the fetus starts breathing (thereby becoming an infant).

Answer 8

Everything else being equal, a human fetus in utero for 21 months will be dead. So, it is not reasonable. How could you make it "reasonable"? Slow down the process by a factor of 21/9, obviously. That would require changes in the infant's genetic code or some sort of (wave hands, queue in the smoke and mirrors) stasis (low temperature hibernation?). Why would we want to do that? Well, only reason I can think of is to either do a quality control of the kid's genome, or to add/subtract to it. Based on the little I know about neural development, this would be a very very bad thing for the kids brain...again, unless something was done to 'fix' the deficit caused by an enormous decrease in stimuli starting at 9 months. Keep in mind that the brain is undergoing a gigantic construction project at and in the months immediately after birth and without the "right" stimuli, the resulting structure will not have been constructed correctly. I can't really see any good reason that this could be useful. 21 months is just waaaay too long. Also keep in mind that at some point, a placenta just will not be able to keep up with the body's demand for nutrients and oxygen... and guess what? that happens at about 9 months. So, even if you slow it down, you shouldn't expect a more developed newborn, just the opposite, you'd expect a LESS developed one (since it will necessarily have been deprived of critical nutrients).

Answer 9

I can't understand why a baby would be less developed if it stayed incubated longer. Nature has some level of intelligence and ability to adapt to its environment. If no placentas have been given a chance to prove that they are perfectly capable of housing babies in a womb for 2 years, then how can it be said that they are not still able to provide? So long as the mother is eating etc, maybe a more aged placenta becomes stronger with time and more efficient because it has gotten used to the body. Thus giving birth to a baby whose lungs are developed possibly neck, the rest will incubate on the back burner until it actually breathes air. In the meantime your drinking water etc no reason why the amniotic fluid fluid cannot replenish itself. Low amniotic fluid is already been deemed a scam. And of course not all humans development and intelligence is the same otherwise we would all be Bill Gates so the abilities if a baby in some cases can be exceptional, though rare inded .