Our Gemara on Amud Beis discusses a case of a woman who was lacking in menstrual blood, and also possibly those who tend to have less menstrual and virginal blood. On the one hand it is considered an advantage, in reducing questions about Niddah. But it also presents a problem regarding fertility.
This ambivalence about menstruation on a practical level is also discussed in a mystical sense by Rav Tzaddok in Peri Tzaddik (Lag Baomer 5):
He notes that Yechezkel (36:17) refers to the Jewish people's status in sin as the impurity of the Niddah. He sees this as an optimistic message. Unlike the ritual impurity of a corpse which forbids the Cohen from entering, the impurity of Niddah does not ban entry. In addition, it is temporary and ends with reunification between husband and wife. God is telling the Jewish, we are distant now, but we can be reunited.
But there is more to the duality and ambivalence regarding Niddah. He says that though many midrashim see the blood and pains of Niddah as part of the curse put on the woman (see Shabbos 31b and Eiruvin 100b) , there also is a redemptive factor. The ability to have children comes directly from the biological menstrual system. Having children is a form of repair to the loss of immortality as we live on, perhaps even better, through developing our progeny.
Even the Talmud’s description of the Niddah blood hints at this idea: “Just as leaven is fortuitous for dough, so too, blood is fortuitous for a woman. And it was taught in the name of Rabbi Meir: Any woman whose blood is plentiful, her children are plentiful.”
The comparison of blood to leaven hints at another rabbinic metaphor, which describes the Yetzer Hara as the שאר שבעיסה the leavening in the dough (Berachos 17a). This is the potentially sinister but also catalyzing element that transforms humble matzah into fluffy, proud bread. Like the blood of Niddah, on one level it represents a contamination of the original purity by mortality and physicality, but on the other hand is really the basis for all of civilization and progress. As the husband and wife enact their physical lives, they also are channeling and arousing spiritual archetypes of physical disruption of spirituality, followed by the opportunity for redemption, immortality and expansion through the experience of return and reunification of physical and emotional matter in this world and the next. This leads to reproduction and productivity.
This is an important principle in psychology, nature and spirituality. The problem itself often contains the seeds for the repair.