Are push up bras good/bad after Breast augmentation (once cleared for bra use/wear)? Do they cause breasts to sag post op ?

In my opinion, there is no evidence that the type of bra that is worn once the breasts have settled(after about three months post-op) will make any difference in the breasts over the long run.  So you should wear whatever is comfortable and suits your fashion sense.  Best wishes.

  In my opinion, wearing a pushup bra after breast augmentation, once the breast implants have settled into place, is perfectly okay.  With different types of implants and different types of operative techniques, the time that it takes for the breast implants to settle into place can be different.  Be sure to run this by her surgeon.

Once you are cleared to wear regular bras by your surgeon, push up bras are fine. Before doing so, get your surgeon's advice. Good Luck.