Much of Parshas Tazria focuses on the laws of tzara'as - when does tzara'as render a person or a garment tamei and when does it not do so. But before the Torah begins its discussion of tzara'as, it first talks about the halacha of tumas leidah. "If a woman conceives and gives birth to a boy, she shall be temei'ah for seven days...And if she gives birth to a girl, she shall be temei'ah for two weeks. (Tazria 12:2,5)" This is the Torah's introduction to the laws of tzara'as. The question is what is the connection between these two halachos?
What's more, the halacha of tumas leidah itself seems puzzling. Why should a woman become temei'ah when she gives birth to a baby? We commonly associate tumah with death. Giving birth is the exact opposite. Why should bringing a new life into the world make a woman temei'ah?
The Gemara (Arachin 16a-16b) lists a number of different aveiros which cause tzara'as, the most famous of which is lashon hara. Chazal comment that it is for this reason that a metzora must be quarantined outside the camp as a punishment for having separated between people through his divisive speech. Rashi, at the beginning of Parshas Metzora, mentions a second cause for tzara'as. The posuk (Metzora 14:4) says that as part of his purification process, a metzora must take a branch from a cedar tree, a red thread from a worm, and some grass. Rashi quotes the Midrash which explains that tzara'as afflicts a person when he acts with arrogance and haughtiness like a tall cedar tree. What is his cure? He should lower himself like a worm and lowly grass.
It seems as though Chazal are giving two separate causes for tzara'as - lashon hara and arrogance. But actually these two aveiros might be related to each other. What Chazal might be alluding to is that sometimes a person speaks lashon hara because he thinks too highly of himself, so he belittles other people. He does not appreciate their value. Other times, a person might speak lashon hara because he has low self-esteem. He wants to be able to think highly of himself, so he knocks other people and denigrates them in order to build himself up.
What is the cure for such an individual? He has to correct his perception of himself relative to other people. If only he would realize that everyone has a unique role to play in this world, and that no one person's contribution is more important than that of anyone else, he would not denigrate other people. If only he realized the value of his own contribution, he would not feel the need to speak ill of other people just to enhance his self-worth.
Perhaps this is why the Torah prefaces its discussion of tzara'as by first talking about tumas leidah. Why does a woman become temei'ah when she gives birth? One reason might be because a living Jewish child has left her body. It does not matter that this young baby has yet to accomplish anything, that on the surface there seems to be nothing special about this child. What matters is that the baby has the potential to act with kedusha, to fill its life with Torah and mitzvos. So when its mother gives birth and she loses this source of life, she becomes temei'ah.
The halacha of tumas leidah highlights the idea that all Jews are created equal. What generates tumas leidah is the inherent value of each and every Jewish child. Non-Jews are not subject to the halacha of tumas leidah (Toras Kohanim, Tazria 1:1) because they don't have the same potential for kedusha that a Jewish child has. But every Jew is endowed at birth with an ability to live with kedusha. At birth, every Jewish child, male or female, has the same natural connection to kedusha and ruchinyus that he or she had in the womb. And that is why the birth of a Jewish child generates tumah for its mother because by giving birth the mother has lost this source of kedusha.
This is the lesson that a metzora must internalize in order to do a complete teshuva for his lashon hara and arrogance. He has to appreciate that no Jew is more important than any other because everyone has the potential for kedusha; every Jew has a special role to play in the mission of Klal Yisrael. That is why the Torah mentions the halacha of tumas leidah right before it begins its discussion of tzara'as to emphasize that the way to avoid the aveiros which cause tzara'as is by being sensitive to the message of tumas leidah.