Why is it possible to take methadone in pregnancy? I thought it was addictive.

It is. Methadone safety in pregnancy was determined by comparing heroin addicts versus Methadone maintenance patients in large studies. The patients on Methadone and their babies did better than the actively using heroin group. This just means Methadone is better than heroin, not that Methadone is better than no methadone. It is an addictive opioid and no Methadone is better than some for a baby.