Reasons for late abortion: anencephaly
A baby born without a brain cannot live and will never become conscious. Sometimes a defect like this is not detected until late in a pregnancy.
When doctors detect that a fetus is developing without a brain, there's no reason to make the pregnant woman go childbirth or through the rest of pregnancy.
It's best to let the woman end the pregnancy and recover, keeping her bodily resources intact for the next pregnancy.