Is it permissible to undergo surgery to enlarge the breast due to its sagging after breastfeeding, which makes it ugly and unsatisfactory to the husband and oneself?

If the sagging is severe, causing psychological distress and disfiguring the appearance, and the operation is safe and likely to be beneficial, then there is no harm in performing it to remove the defect. However, if the sagging is normal, such as that experienced by a nursing mother, then it is not permissible to remove it because it falls under forbidden beautification. Sheikh Ibn Uthaymeen mentioned the permissibility of tightening sagging breasts if it is to remove a defect.