We are probably going to create colonies on Mars in few decades or centuries, so which steps have been taken by NASA or other space agencies to find out if child birth is possible in a lower gravity than Earth's?
Mammal experiments have shown that zero gravity does not affect fetuses in the late stage of gestation. http://curious.astro.cornell.edu/physics/153-people-in-astronomy/space-exploration-and-astronauts/the-future-of-human-spaceflight/960-can-a-human-give-birth-in-space-intermediate
Gravity-friendly birthing postures (e.g. kneeling or squatting) are common in many countries, but most deliveries in the USA have the mother flat on her back with legs up. Gravity is at best neutral to the process, if not an impediment. Babies continue to be born nonetheless.
The main health concerns for space travel, regardless of age, are atrophy from long term low gravity and cellular damage from increased radiation exposure.