"Space Babies" Kia Sorento 2013 Super Bowl Ad
This probably isn't the start of a new and glorious career (thank you anyway, honey), but it did get me wondering about the logistics and limitations of the question. Let's say that some nice couple on the International Space Station decides that they want to have a child before their contract is up (secretly, of course, because apparently sex is expressly forbidden aboard the ISS). Would it be possible for them to conceive, and later have, a normal, healthy child?
It seems that the short answer is "no." According to research led by Joe Tash, a biologist at the University of Kansas, the high-energy radiation and so-called microgravity (10-3 G) that astronauts are subjected to during long spaceflights can have serious negative effects on their reproductive systems - namely, plummeting sperm counts and shriveling eggs. Similar concerns about the detrimental effects of space-level radiation are well-publicized. In fact, in 2010, China announced that it would require all of its female astronauts to be married with children in an effort to minimize the impact of the reproductive problems women might experience upon their return.
On the up side, a 2005 study out of the University of Texas showed that many female astronauts easily became pregnant after coming back to Earth; however, the same study also revealed a higher-than expected miscarriage rate among those pregnancies. Radiation could be to blame for these losses, but an equally plausible explanation could involve the effect of microgravity on human sex cells. Research published in 2009 in the Public Library of Science ONE showed that despite successful fertilization, many mouse embryos that were exposed to microgravity conditions stopped dividing before they reached crucial stages of development. Furthermore, Joe Tash's research also revealed severe dysfunction in the reproductive organs of female mice after about two weeks of flight aboard the space shuttle Discovery. The effect in these mice was so extensive that many of their follicular cells (the cells that produce eggs) had died and their ovaries had started to shut down.
Eek. But let's say that this daring couple is also very lucky, and they do successfully conceive a child. (We'll go ahead and skip over the logistics and precariousness of actually taking a pregnancy test in the first place.) Research suggests that while some animals, such as salamanders and fish, appear to gestate normally in microgravity environments, the outlook for mammals is decidedly more complicated. For one, some studies have suggested that microgravity can lead to fetal malformations in utero, including failure of the neural tube (the primitive brain and spinal cord) to close like it is supposed to. For another, mammals that were gestated in microgravity environments appear to have an altered vestibular response, the sense that allows a person to achieve a sense of balance and direction. Like all of our other senses, it requires stimulation to develop properly. Babies born in a microgravity environment would never learn to prefer one direction over another, leading to a compromised vestibular sense and big problems once they landed on Earth. Studies with rats have shown that a proper vestibular response can be learned over time; however, it is unclear whether that would hold true for human infants, especially if those babies spent months or even years in microgravity conditions.
And when we consider that the human body requires weight-bearing in order to stay strong, we come to another problem. Even adult astronauts have to remain vigilant about their exercise routine in order to avoid muscle atrophy and bone loss that can easily occur during long spaceflights. To a very small, rapidly developing body, these threats could be catastrophic. Additionally, the fluid shifts that commonly occur in astronauts living in microgravity environments could be far more dangerous for infants and small children, since their bodies contain more water than those of adults. Not to mention the increased risk for electrolyte abnormalities, changes in blood vessels, compromised cardiac functioning, and altered circadian rhythms that microgravity creates.
So. Overall, I think it's safe to say that conceiving, carrying, birthing, growing, or even thinking about space babies is probably not a good idea. NASA would do well to continue funding research into the effects of spaceflight on both male and female sex organs, but until we can manipulate gravity and block space-level radiation, reproduction in space just doesn't appear to be something our species is meant to experience.