FailedPregnancy
A failed pregnancy, or "miscarriage", or "natural abortion", is when the infant dies in the uterus (womb), while still in the mother. Tragic as this is, it is usually no one's fault. I guess a stillbirth?, where a child is born already deceased, could be considered a kind of failed pregnancy.
I don't like the term "miscarriage" because it makes it sound like the mother? did something wrong, which she usually didn't. It is the most common term for this event, though. Another term is "natural abortion", which I don't like because it implies that abortion is fine and normal, which I don't think it is.
A failed pregnancy is a tragic event and it is not wrong for both the mother and the father? to be devastated and/or experience a lot of grief. It used to be that people didn't talk about it, and had to carry their grief silently, but it's become more open in the recent past, which I think is a good thing.