Forbes has a short piece on the ethics and practicalities of having babies on Mars: Birthing Babies On Mars Will Be No Small Feat.
They cover the core reasons why having children (at least for the first fifteen or so years of settlement activity) is a taboo in the Ares Project universe: mainly, there’s no telling whether it will be safe to do so, and in small commercial settlements, babies and small children will consume scarce economic resources without near-term economic return. This originated early on in writing In the Shadow of Ares in the need to explain why Amber Jacobsen was still the only child on Mars after almost fourteen years of settlement activity, and the more we thought about the reasoning behind such a taboo the more real-world sense it made (and the more influence it had on her character and the story, especially the coming-of-age subplot).
Of course, in Ghosts of Tharsis and “He Has Walled Me In” we show that this taboo is starting to break down. This happens in large part because several of the settlements are large enough by the time these stories take place to absorb the economic impact.
[via Transterrestrial Musings]