What are the necessary conditions for an unborn child to inherit?

Primary text

The unborn child inherits only upon two conditions. First, it must be known that the fetus existed at the time of death. This is confirmed if the child is delivered in less than six months. If delivered later, the situation depends on whether the woman has a husband or master who had access to her. If access existed, the child does not inherit unless the current heirs affirm existence at the time of death. If the woman was not accessible (due to lack of a husband/master, absence, or mutual avoidance), the child inherits up to the maximum duration of pregnancy, which is four years in the soundest narration, or two years in another opinion.