or don't throw ur old panties....use them after delivery as they r comfortable & after reuse of them can easily throw them...

there are disposable panties available too. quite useful- use n throw fr initial few days. they r very comfortable as the elastic is very soft, wont hurt on tbe stitches n expand to quite a large extent as per size.  check them out.

Better to buy a little larger one,will be more useful during first few weeks