After The Fall, reproductive choices will be decided by genetics. Only the best genetic material will be allowed, and only the upper classes allowed to raise children.
In the future, when everyone is genetically perfect, maybe it will be different. For now, this final generation of imperfect women have become a commodity to be bought and sold for the good of the whole.
Sara is pregnant with a child that she will be expected to give up at birth. Why should she care, the baby is not of her genetic material anyway. But this is her third successful surrogate pregnancy and after this, she'll be sent to the outlying colonies to work, and die.
Unless she can escape.