Just a couple of thoughts to add...
This seems like a very personal killing, in my opinion she knew her killer. There seems to be a lot of rage here. It could be a spouse/father of the baby. Or some kind of honour killing by a family member (her father or brother) it was still shameful and taboo to be an unwed mother in those times, especially in smaller religious communities.
Or it could even be a case of incest (any male family member) and she was killed to keep it a secret.
Is it possible to tell whether the birth was a hospital delivery or whether it was done with no medical help?
If she had the baby in a hospital after running away/going missing from family and friends and they were never even aware of the pregnancy. Or she had the baby and then disappeared but was not reported missing.