Human pregnancy in zero gee is a complete unknown and research for animal gestation in zero gee* is limited to a small number of mouse pups.
So is it safe to assume that having a kid in space or even on Mars is a bad idea?
* gee = means 1 Earth gravity or 9.8 m/s2
Co-Ed Space Crews
It is fair to assume that the first crew to Mars will be a co-ed affair. Not only is it politically correct to have a mixed gender crew but it will also be good for morale for when people, umm, you know, feel the urge. Being locked up in a small craft for months on end could challenge the psyches of even the most stalwart astronauts.
So a mixed gender crew combined with the birds and the bees means that you will want to avoid pregnancy at all costs.
This also means that everybody will need to get their tubes tied. Development of a fetus on the way to Mars and even on Mars is an unknown for at least two reasons; zero gee and high radiation.
High Radiation
The trip to Mars will be in a glorified tin can. A high tech tin can but a tin can nonetheless.
It costs money to launch mass off of the Earth's surface and it also costs money to accelerate a ship up to the speed needed to get it on its way to Mars. Therefore the less mass you send to Mars the cheaper it is. This also means that the shielding on the ship going to Mars will need to be at the minimum necessary to keep the crew alive.
On Earth radiation workers have specific annual dose limits that are higher than those for the general public. This means that if you work at a nuclear facility you agree to these higher limits. Pregnant women or women who are trying to get pregnant are disallowed from such tasks because the embryo and fetus are very sensitive to ionizing radiation. The consequences of radiation exposure at this stage of life could be growth retardation, impaired brain function, malformations and cancer.
Apparently, Mars has no structured global magnetic field and very little atmosphere. This means that when a solar storm hits Mars the high speed charged particles will have little to deflect or stop them. All of this adds up to a possibly higher radiation dose on Mars compared to the Earth even though Mars is farther from the Sun than the Earth.
So, having kids on Mars means living underground and away from the surface.
Fetal Development In Zero Gee
The little research on this topic seems to indicate that getting pregnant will be harder in space due to the effect on embryos implanting on the uterine wall. If an embryo does manage to implant then some papers suggest that the lack gravity may have detrimental effects on the baby.
In the earlier stages of pregnancy the fetus is in a neutrally buoyant environment but at week 21 to 22 the baby's weight is such that it will experience up to 60% of its own weight.
The weight in these latter stages of pregnancy will condition the bones, muscles and cardiovascular system. A child born in space and maybe even on Mars might be at a developmental disadvantage compared to the Earth born.
Unknown Effects?
Of course there may be many possible unknown effects due to being conceived and gestated in space and/or Mars. Could nerve fibers be affected due to the lack of gravity. Could zero gee affect eyeball development and impair the eyesight of the space born? What about brain development or the digestive system?
The immune system of the space born might be unchallenged compared to the Earth born as they will not be exposed to the same amount of viruses and bacteria as we are. Will being born in space mean that you can never go back to Earth because it will be a virtual death sentence?
Much work needs to be done to determine all of the potential effects and downsides before people should be allowed to create new generation in space or the asteroids and planets.
Image credit: Carlos Augusto Naves Bueno Filho link
CC BY-SA 3.0 license
Simulating Earth Gravity on Mars
In space, gravity can be replicated using a spinning space station and usually these are depicted as large rotating wheels with spokes as on a bicycle wheel. On Mars there already is gravity, it is weaker than on Earth (38% of Earth strength) but it is still there.
This means using another geometry which is a spinning truncated cone (see image). If you choose the wall angle right and the rotation speed correctly then you can simulate Earth gravity for those one the inside surface. The cone will need to be large enough to minimize vertigo when a person stands up but that does not feel like a showstopper.
Closing Words
Space travel is a whole new field for humans. The dramatic and attention grabbing aspects like rocket launches and moon landings are actually only a minor part of the whole endeavour.
A huge amount of the behind-the-scenes and mundane but necessary science and technology development still needs to be completed before humans could ever be consider themselves to have mastered travel in our solar system. One of these of course is how to have kids in space.
Until that day, if you are going to Mars you will first need to make a trip to the doctor's office for a quick procedure.
Thank you for reading my post
Post Sources
Rat gestation during space flight: outcomes for dams and their offspring born after return to Earth - US National Library of Medicine National Institutes of Health
Detrimental Effects of Microgravity on Mouse Preimplantation Development In Vitro - PLOS.ORG
The fetus cannot exercise like an astronaut: gravity loading is necessary for the physiological development during second half of pregnancy - US National Library of Medicine National Institutes of Health
Could a fetus properly develop in micro/zero-gravity? - Stack Exchange
Animals Born In Space Have A Hard Time Adjusting To Life On Earth - Business Insider
Information for Radiation Workers - NRC
Radiation and Pregnancy: A Fact Sheet for Clinicians - CDC
Possible Health Effects of Radiation Exposure on Unborn Babies - Pennsylvania Department of Health