I smoked and drank through my first pregnancy (though not heavily), without any ill effects to me or my baby - except for the first three months when I experienced a minimal amount of nausea and tiredness in the evenings
I stopped smoking during my second pregnancy but still had the odd drink, again without any ill effects to my baby or me - except tiredness in the first three months.
At the onset of my first pregnancy my doctor instructed me to take iron tablets, even though there was no indication that I needed them. At the onset of my second pregnancy a different, younger, doctor said she was not prescribing iron tablets. She said that research had indicated that taking iron tablets when they were not needed could be damaging.
I think most people would now agree that it would not be wise to drink like a fish or smoke during pregnancy but I also think some of the restrictions on pregnant women are far too prescriptive and alarmist.