The mere act of quitting smoking will induce your body to start cleansing itself so to speak. The inflammatory changes caused by smoking will start to reverse (in fact they already have). Chronic changes however may be slow to reverse, if ever. But you will definitely notice and sense improvement in your breathing and exercise tolerance within a few days. There are no medications to rid the body of the toxins associated with smoking. Just make sure you follow a healthy lifestyle and abide by your obstetrician's instructions.