It appears intent is the key here as to whether the Lord considers it murder. He references murder/killings to evil intentions such as hate. And calls it of the evil one.
You are of your father the devil, and the desires of your father you want to do. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. When he speaks a lie, he speaks from his own resources, for he is a liar and the father of it. John 8:44
You have heard that it was said to those of old, 'You shall not murder,' and whoever murders will be in danger of the judgment. But I say to you that whoever is angry with his brother without a cause shall be in danger of the judgment. And whoever says to his brother, "Raca!" shall be in danger of the council. But whoever says, 'You fool!' shall be in danger of hell fire."This is the message you have heard from the beginning: we should love one another, unlike Cain who belonged to the evil one and slaughtered his brother" (1 John 3:11-12)
Choosing to save the Mother's life over the babies in a very difficult situation is not harboring "evil intent" though it may be the wrong choice in the eyes of our Lord.
Imo, it is not the same as cold blooded murder which requires evil intent.
Our Military fight to save our lives, yet it is not considered "murder" due to the fact it is in self-defense which is not considered evil intent. A mother who chooses her life over her babies could be similar, it is partially self-defense. Yet it may be God's will she give up her life for her babies. Seems there are many factors to consider, and much prayer before making such a difficult decision.