hi. first relax, most important factor is that you are aware that smoking and drugs are not at all good for your pregnancy, so please don t use them in future. as far as your current pregnancy is concerned, it depends on which drug/s you used and whether you used it during your conception time. i suggest that you take folic acid, if you have not started as yet and go for regular antenatal visits and investigations. now-a-days, there is a stepwise approach in which regular screening tests and ultrasounds are done at specific times during pregnancy, which help us to ensure that the baby and expecting mother are doing fine. all the best.