As plans for missions to Mars speed up, so do questions on how the human body might cope. A return trip to the red planet would give good enough time for somebody to grow to be pregnant and even give birth. But could a pregnancy be conceived and carried safely in space? And what would occur to a baby born removed from Earth?
Most of us rarely consider the risks we survived before birth. As an example, about two thirds of human embryos don’t live long enough to be born, with most losses happening in the primary few weeks after fertilization; often before an individual even knows they’re pregnant. These early, unnoticed losses normally occur when an embryo either fails to develop properly or to implant successfully within the wall of the womb.
Pregnancy may be understood as a sequence of biological milestones. Each must occur in the correct order and every has a certain probability of success. On Earth, these odds may be estimated using clinical research and biological models. My latest research explores how these same stages could be affected by the intense conditions of interplanetary space.
Microgravity, the near-weightlessness experienced during spaceflight, would make conception more physically awkward but probably wouldn’t interfere much with staying pregnant once the embryo has implanted.
Nevertheless, giving birth, and searching after a newborn, can be far tougher in zero gravity. In spite of everything, in space, nothing stays still. Fluids float. So do people. That makes delivering a baby and caring for one a much messier and more complicated process than on Earth, where gravity helps with all the pieces from positioning to feeding.
At the identical time, the developing fetus already grows in something like microgravity. It floats in neutrally buoyant amniotic fluid contained in the womb, cushioned and suspended. In reality, astronauts train for spacewalks in water tanks designed to mimic weightlessness. In that sense, the womb is already a microgravity simulator.
But gravity is barely a part of the image.
Radiation
Outside Earth’s protective layers, there’s a more dangerous threat: cosmic rays. These are high-energy particles—“stripped-down” or “bare” atomic nuclei—that race through space at nearly the speed of sunshine. They’re atoms which have lost all their electrons, leaving just the dense core of protons and neutrons. When these bare nuclei collide with the human body, they may cause serious cellular damage.
Here on Earth, we’re protected against most cosmic radiation by the planet’s thick atmosphere and, depending on the time of day, tens of 1000’s to thousands and thousands of miles of coverage from the Earth’s magnetic field. In space, that shielding disappears.
When a cosmic ray passes through the human body, it could strike an atom, strip its electrons, and smash into its nucleus, knocking out protons and neutrons and abandoning a distinct element or isotope. This may cause extremely localized damage—meaning that individual cells, or parts of cells, are destroyed while the remaining of the body might remain unaffected. Sometimes the ray passes all the way through without hitting anything. But when it hits DNA, it may cause mutations that increase the danger of cancer.
Even when cells survive, radiation can trigger inflammatory responses. Which means the immune system overreacts, releasing chemicals that may damage healthy tissue and disrupt organ function.
In the primary few weeks of pregnancy, embryonic cells are rapidly dividing, moving, and forming early tissues and structures. For development to proceed, the embryo must stay viable throughout this delicate process. The first month after fertilization is probably the most vulnerable time.
A single hit from a high-energy cosmic ray at this stage might be lethal to the embryo. Nevertheless, the embryo could be very small—and cosmic rays, while dangerous, are relatively rare. So a direct hit is unlikely. If it did occur, it will probably lead to an unnoticed miscarriage.
Pregnancy Risks
As pregnancy progresses, the risks shift. Once the placental circulation—the blood flow system that connects mother and fetus—is fully formed by the tip of the primary trimester, the fetus and uterus grow rapidly.
That growth presents a bigger goal. A cosmic ray is now more prone to hit the uterine muscle, which could trigger contractions and potentially cause premature labour. And although neonatal intensive care has improved dramatically, the sooner a baby is born, the upper the danger of complications, particularly in space.
On Earth, pregnancy and childbirth already carry risks. In space, those risks are magnified—but not necessarily prohibitive.
But development doesn’t stop at birth. A baby born in space would proceed growing in microgravity, which could interfere with postural reflexes and coordination. These are the instincts that help a baby learn to lift its head, sit up, crawl, and eventually walk: All movements that depend on gravity. Without that sense of “up” and “down,” these abilities might develop in very other ways.
And the radiation risk doesn’t go away. A baby’s brain continues to grow after birth, and prolonged exposure to cosmic rays could cause everlasting damage—potentially affecting cognition, memory, behavior, and long-term health.
So, could a baby be born in space?
In theory, yes. But until we will protect embryos from radiation, prevent premature birth, and ensure babies can grow safely in microgravity, space pregnancy stays a high-risk experiment—one we’re not yet able to try.