Possivelmente, uma combinação de não se mostrar muito, mexer com ela, e as pessoas que não a conceberem poderiam ter outro filho.
Em "A sala de 100 escritores" Tumblr (que é oficial), as pessoas perguntaram sobre controle de natalidade na Arca, ea resposta é que toda mulher tem um implante contraceptivo, que Aurora foi removido "de alguma forma". Os próprios escritores parecem admitir um pouco de mão até que "estabeleçam" algo.
We get this question A LOT as everyone seems really curious about the Ark views on contraception and multiple births.
We’ve established (as has the book on which the show is based) that the Ark maintained strict population controls. Families were allowed one child (by which those births were planned by removing birth control implants to allow conception and then re-implanting the birth control after the baby is born).
In the case of Octavia, her mother had her birth control removed surreptitiously, (or never had it re-implanted after Bellamy was born. We haven’t established this definitively) thus allowing her to give birth to a second child, which she needed to keep hidden below the floor so as to evade discovery…which, ultimately, failed when Octavia was discovered and imprisoned.
Quanto à parte "oculta", como um comentário avisos, isolamento provavelmente será respeitado na Arca, para medidas de saúde; e quando ela absolutamente precisava se mostrar, se ninguém espera que ela esteja grávida, um bom casaco / levando coisas (Bellamy?) pode ter escondido isso.
Aparentemente Seinfeld usou isso com uma atriz grávida por meia temporada:
Julia Louis-Dreyfus's off-screen pregnancy meant that her character had to spend the latter half of this season hiding her belly behind furniture and laundry baskets.
from an Internet Archive snapshot of Sony Picture's website