Lots of kids suffer worse deprivations than having one parent in jail. Life is tough, but these kids probably have a better than average shot at a good life.
They'll be raised by a wealthy family with every material advantage in life. Some estimates have it that around 1 in 8 children in America go hungry at some point in their childhoods. So even if these kids are just fed regularly, that puts them ahead of millions of children.
The child did not lose a mother, if he/she never had one. Also she'll be out around the time the child will start elementary school. So yes the child will still be in a better spot than 99% of all children in single family households and probably than almost all in low income ones as well.
It's not a question of rights, since she obviously has them, it's a question of 'How fucked up is it to put your desire to have a child over that child's wellbeing.'
At some point in the desire to wellbeing ratio, that equation crosses the line into 'incredibly selfish'. Children aren't just trophies for their parents.
The court doesn't need to mention it to discreetly take it into account. Otherwise why wait until April to begin the sentence? Did they mention the pregnancy there? This is a legal, social, and political orchestration process, not a computational system.
There are lots of reasons the BOP would prefer to avoid incarcerating pregnant women. Surrenders are usually 4-6 weeks out; with the holidays, that pushes out into January. She's not getting that much of a break.