Because of sins such as homosexuality a male soul might reincarnate into a woman's body, and such a woman will not be able to give birth without great merit and the entry of a feminine soul into her as an ibur.
Although women do not reincarnate, they can sometimes come as an ibur into women, together with sparks of new, feminine souls.
There is another possibility when they come as an ibur in some other woman. If that woman conceives, becomes pregnant and gives birth to a girl, then the one that came as an ibur might reincarnate as an actual gilgul in that daughter who was just born.
The Ari will return to this phenomenon further in this section. Sometimes a man may reincarnate into the body of a woman because of a sin, such as homosexuality…
Sometimes a man may reincarnate into the body of a woman because of a sin, such as homosexuality or something similar. This woman who has received the soul of a man will not be able to conceive and become pregnant.
This is a serious punishment. Barren women usually suffer tremendously.
This is because she lacks [the ability] to raise Mayin Nukvin, and she cannot receive Mayin Duchrin.
The concept of Mayin Nukvin (M"N), "Female Waters", was explained somewhat in Chapter 3:8. Its counterpart is Mayin Duchrin (M"D), "Male Waters" or juices that flow from above to below, such as the sperm that is emitted during marital intimacy. In Kabbala, this term refers to all the light and blessing that flow downward from Above.
Obviously, the physical bodies of the partners must be able to function normally in order for procreation to happen. The Ari is adding here that some similar function must also take place in the soul bodies. Souls have masculine and feminine aspects, as it is written, "…He created them male and female" (Gen. 1:27). Furthermore, the rule in the Kabbala is that This World is a sort of reflection of what is contained in the spiritual roots (despite the anomaly under consideration here). Thus, the female soul must also be able to emit juices of M"N and lubrications that draw downward to herself the M"D of the masculine soul. The male soul that is within her cannot…become pregnant or give birth…
In this anomalous case, however, as a result of sin, the soul that is within the female body is not feminine, but male. The female body in this case will be able to function normally in a biological sense, to emit female juices and lubrications. However, the male soul that is within her cannot do so. The consequence will be that this woman cannot become pregnant or give birth.
This woman will need great merit to enable her to become pregnant and give birth. The only way it can be done is that some other feminine soul must enter her as an ibur. In partnership they can raise M"N, conceive and give birth.
One has a female body; the other is a female soul. She cannot give birth to boys, but only to girls…
However, she cannot give birth to sons for two reasons. The first is [as follows:] There is a verse that says, "…If a woman puts forth seed, and a male child is born" (Lev. 12:2).
In the Talmud (Berachot 60a, also Nidda) it is said, "If a woman 'puts forth seed' first, then a boy will be born. If the man puts forth seed first, then a girl will be born."
In this case, the woman is a male, just like her husband.
In this case, whichever one biologically "puts forth seed" first, in the spiritual realm both partners are masculine souls, and it will always be the male who puts forth seed first. Therefore, the child must be female.
She cannot give birth to boys, but only to girls. At the time that she gives birth, that feminine soul enters into the fetus…
The second reason is that the feminine soul that has entered her does so only as an ibur in order to help her become pregnant and give birth. Once this woman gives birth, that soul does not need to stay there any longer for no reason. At the time that she gives birth, that [feminine] soul enters into the fetus as an actual gilgul, and not as an ibur, like it was at first. That is why the child that is born must be female and not male.
The child that is born will be the gilgul of the feminine soul that entered the mother as an ibur. Since the feminine soul is not itself tainted with any sin of illicit sexual relations, she must enter a feminine body. Therefore, the child will be a female.
In summary, any woman whose soul is a masculine soul, as explained beforehand, cannot give birth to a male, but only to a female. The female child that is born will be the same feminine soul that originally entered to help out.
In Chapter 38, the Ari will actually relate that the first wife of Rabbi Chaim Vital was the gilgul of a soul of the type discussed here in this section. That is why she could not give birth to a son. Rabbi Shmuel Vital, the son of Rabbi Chaim, through whom the Lurianic tradition was transmitted, was the son of Rabbi Chaim's second wife, who was actually his soul mate.
[Commentary by Shabtai Teicher.]