The laws of purity and impurity are a part of the Torah that is seemingly beyond human conception. The Torah defines these laws in Bamidbar (19:2): “This is the chok of the Torah.” Rav, the great Amora, when discussing laws relating to our parasha, states: “It is one source – the Torah made it impure, and it made it pure” (Nida 35b). Nevertheless we will try to explain a few principles and what they are meant to teach us.
Many have tried to explain the sequential significance of “Should a woman give forth seed and give birth to a male” (Vayikra 12:2). A baraita seems to take things literally: “If the woman ovulates first, she will bear a male. If the male’s seed is first, she will bear a girl.” Rabbi Tzadok cites further support for this correlation from the pasuk, “These are the sons that Leah bore for Yaakov in Padan Aram, along with Dina, his daughter” (Bereishit 46:15). Still, it is hard to understand what the Torah is hinting at and what the various rabbis are saying.