What marks the end of the postpartum phase?

The end of the postpartum phase is marked by the mother's body returning to its pre-pregnancy form, which includes physical, hormonal, and emotional adjustments. This period typically focuses on the physiological changes that a woman experiences after childbirth. While it may take several weeks to months for the body to heal and return to its pre-pregnancy state, the completion of this process signifies that the most intense physiological aspects of postpartum recovery are concluding.

The other options do not accurately reflect the end of the postpartum phase. For instance, a hospital discharge does not indicate the end of postpartum recovery, as the body continues to change after leaving the hospital. Additionally, a baby learning to walk is a developmental milestone unrelated to the mother's postpartum recovery. Lastly, one year is often considered a significant milestone in a child's development, but it does not delineate the postpartum phase specifically for the mother. Thus, the correct answer highlights the physiological transition that the mother undergoes post-delivery, making it a definitive marker for the end of the postpartum phase.