If anyone thinks that the situation with practicing males -- what they should or shouldn't undertake, what is safe or unsafe -- is unclear, I can assure you that the situation with women is a hundred times worse, and reliable gender-specific instructions are a hundred times harder to find.  (Well, don't get me started I tell myself, and abandon the desire to go into the why's and wherefore's.)   I've come across these opinions though (leaving out a few that I don't find worthy of consideration, like the "slaying of the Red Dragon" and "devolving the breasts" misogynistic crap):   1. Women don't gain much from focusing on the lower dantien, which is naturally well developed in them anyway, and must instead use the middle dantien in most situations where males are asked to use the lower one.  By focusing on the LDT males are trying to create a "spiritual womb" of sorts and take their focus down from where it innately tends to "pop up," excessively exciting the heart-mind and neglecting those parts of their spiritual life that are about nurturing, patience, the hidden, deeply yin potentials.  Women, by the same token, should lift their spirit that is already down by virtue of their innately more yin nature, and develop power in their heart and in their breasts, the outward, "yangmost" part of their femininity.     2. LDT practices are unisex.   3. Women can fix their female-specific difficulties (e.g. menstrual) by focusing on the LDT.     4. Women can exacerbate their female-specific difficulties (e.g. menstrual) by focusing on the LDT.   5. It depends on the specific practice, school, and goals.   Personally, I find that reverse breathing into the LDT while the breath is in no way forced is at least not harmful, but I went through a lot of deep feeling body-inclusive healing which was accompanied by spontaneous reverse breathing at a humongous rate and for unbelievable stretches of time with no sign of hyperventilation because it was happening in context, as part of the systemically and sequentially (important!) retrieved earliest memories.  I believe any forced or excessively focused LDT breathing can trigger those unconscious systemic (not in the head) memories out of sequence and out of context, and that's where the danger really lies.  No one who hasn't connected their unconscious repressed earliest memories to consciousness knows what lies beneath.  We repress for a reason and forget for a reason.  I wouldn't raise the sleeping dogs just to see if they bite.  They do.