ומפני שאין אדם שעובר עליו צרה וצוקה בעולם הזה אם לא יחטא... והיולדת סבלה צרה וסכנה בהיותה על האבניים לכן הייתה מקריבה חטאת.
There is no man that suffers in this world who did not sin. . . and the woman who gave birth suffered and was in danger in labor, therefore she has to bring a sin offering.
רבנו בחיי ויקרא י"ב, ז
ויתכן לפרש שאין הקרבן הזה מצד חטא של עצמה רק מצד אמה שהיא היתה אם כל חי, כי לולא החטא ההוא היה האדם מוליד עם אשתו שלא בדרך תאוה וחשק אלא בדרך הטבע הגמור, כטבע האילן המוציא פירותיו בכל שנה שלא בתאוה, והיולדת הזו כאמה בתה במעשה החטא, כי הענפים הם מקולקלים בקלקול השורש, ועל כן יצריכנה הכתוב קרבן לכפר על החטא הקדמוני...
And it is logical to explain that this sacrifice is not due to her own sin, rather due to the sin of the mother of all (Eve), because if she did not sin, then man and woman would procreate not with desire and lust but in a totally natural way, naturally like a tree that gives fruit every year without any desire, and this birthing woman, the daughter is like the mother in terms of her sin, because the branches are corrupted like the root is corrupted, and therefore the Torah requires a sin offering to atone for the primal sin.
Rabbanit Sharon Rimon
Quite simply, we do not think about childbirth in terms of “sin”; rather, we perceive it as a positive process. Is it not possible, then, that the sin offering brought by the women after childbirth is not the result of sin, but rather for some other reason?
ספרא ל"ה, ג
כל מקום שהיא באה על חטא הקדים חטאת לעולה. כאן, שאינה באה על חטא, הקדים עולה לחטאת.
Wherever a sin offering is brought for a sin, the sin offering is mentioned before the burnt offering. Here, since it is not brought for a sin, the burnt offering is mentioned before the sin offering.
Rabbanit Sharon Rimon
The concept of impurity is abstract and therefore difficult to define. In the world of pure material, there is no impurity. Likewise, in the spiritual world that is completely cut off from the material world, there is no impurity. Impurity is manifest only in the connection between these two worlds. And what is common to all types of impurity is that they are brought about specifically through death. Impurity comes about where there is a separation of material from spirit. It is this parting that the state of impurity signifies.
The process of childbirth is the opposite of death. During birth, a new connection is made between the material world and the spiritual world, and a new life comes into being. Why, then, does this situation cause impurity?
The infant that is born, representing the new connection between material and spirit, is not impure. It is the mother who is rendered impure – not because of the newborn infant, but because of a “death” in a different sense. Firstly, while the infant has begun a new life, the mother has lost a life which, until now, has been contained inside her. Secondly, at the start of the embryo's development, some of the embryonic cells become the placenta, which takes root in the womb and nourishes the fetus during the pregnancy. At birth, the infant – emerging into new life – parts from the placenta. The placenta, which had started off as some of the embryonic cells, and later nourished the developing embryo and fetus and allowed it to grow, leaves the body, and in a certain sense one may say that it is dead.
Rabbanit Sharon Rimon
The birth process involves a huge, mighty collision between the material world and the spiritual world. It is no coincidence, it seems, that this collision comes about specifically amidst the process of birth. The creation of man is bound up with the special combination of material body, flesh and blood, and spiritual soul – the image of God. This combination is no simple matter, and it is therefore specifically at childbirth that the two worlds collide with such force. The woman is in the middle of this collision, a partner in this clash.
The woman experiences most powerfully the physical strain that her body endures, to the extent that she may sometimes become disconnected from the greatness of the process, and feel herself prepared to forego any further pregnancies.
Perhaps the Midrash is teaching us that she must bring a sin offering for this situation, in which the body (and its travail) conquers and dominates the spirit.