Is it permissible to abort the fetuses exceeding two in an IVF procedure—after two months of fertilizing and implanting four ova—to avoid spontaneous miscarriage, and is this considered killing a soul?

Aborting a fetus is forbidden because it is an assault on God's creation and a corruption of progeny. The prohibition becomes more severe after forty days. If the soul has been breathed into it (after 120 days), it is considered the killing of an innocent soul. Exceptions are made for cases of necessity or dire need.