Even though a woman is exempt from the commandment of Pru U'rvu, she is partners with her husband who is obligated to fulfill this mitzvah. As such, she should try to the best of her abilities to help her husband fulfill this obligation. If a woman feels that she is no longer capable of bearing any more children – whether due to physical, emotional, or other factors – then she has done her utmost and they are not held responsible for the fact that Hashem did not bless them with children of both genders. She is not required to push herself beyond what she feels are her limits to enable her husband to fulfill this obligation (which is clearly not in their total control). A couple in this situation may wish to consult with an experienced, empathetic rabbi or mentor for further guidance.

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