Do you buy new bras when you are pregnant? My bras seem to gonna burst anytime, unable to cover much too.

Yes a lot! First of all your boobs will definitely start to swell as it prepares for milk production. Secondly with the growing uterus and belly you will find the rib cage area start to feel tight so definitely have to buy bigger bra. What you can do is get a bigger size and standby bra extender so you don't have to keep buying new ones