Even if it transpires that the doctor deliberately gave an excessive dose and killed the baby, there doesn't seem to be much moral logic in punishing her for ending the baby's life a little faster than she was planning to end it, legitimately, anyway! Every step leading up to the doctor being in prison is perfectly reasonable, but they add up to horrible unintended consequences.
I think it's right to prohibit euthanasia, because although in theory I accept that it can be moral for a doctor to assist a patient to commit suicide, in practice there is no way to enforce the law to prevent its abuse by those who want to murder "undesirables". In a society where people with disabilities, poor people, and old people were fully valued, legal euthanasia would be morally good, but we're a million miles from such a society. I think it's right that causing death by giving the wrong dose of sedatives should classify as murder (or manslaughter depending on intent). I even think it's right that the accused doctor has been temporarily imprisoned; the Swedish legal system jails people arrested on a murder charge, purely in order to take witness statements without the suspect interfering in any way. Once this process is complete, the doctor will be released on bail and await a full trial like any other criminal defendant.
It seems likely that the doctor will be found innocent when the case does come to trial. If not, I foresee a new unintended consequence: doctors in an end of life situation may be reluctant to give adequate pain relief in case they are held criminally responsible for hastening the patient's death. There has to be a distinction between active killing, and simply ceasing treatment (otherwise doctors would have to go to extreme lengths to save patients in every case, and nobody could ever be removed from life support). The problem is that dividing line is ludicrously fine in practice.
When I was a kid we had a neighbour who was found to be carrying a foetus with spina bifida. Being Catholic, she would not consider abortion, but when the child was born, simply didn't feed her until she died. I can't help thinking that it would have been "kinder" for the baby (if you believe that an unborn child has the status of a baby) to be killed by a lethal injection at an early stage in pregnancy, than to be brought to term and then starved to death. Similarly with this case: surely being put to sleep with an excessive dose of sedatives involves less suffering than being taken off a ventilator. Yet, on a technicality at least, the crueller alternative avoids active killing.