Do smoking and drinking harm the baby? Both alcohol and nicotine use at any time in pregnancy have well-documented adverse effects on prenatal brain development. Adolescent problems with aggression and school truancy have been traced to maternal alcohol use in pregnancy.
What about nicotine replacement patches or gum or vaping? Nicotine is the offending agent and regardless of how it is delivered, from cigarettes or nicotine replacement. Nicotine adversely affects fetal brain development and later childhood behavior. 
What about Chantix (varenicline) or Wellbutrin (bupropion)? Varenicline, like nicotine replacement, works by blocking receptors activated by choline in the baby’s brain. We therefore do not recommend varenicline. Bupropion is a better choice. It has proven safe in pregnancy and will help about one-third of mothers quit during pregnancy, provided that they take the drug throughout the rest of their pregnancy.
Can choline or prenatal vitamins help? Higher levels of choline positively affect the baby’s brain development, even in the presence of smoking. Choline targets the receptors that nicotine blocks. Choline with prenatal vitamins has also been shown to block some adverse effects of alcohol on the baby’s brain development.
Read more: Jacobson SW, Carter RC, Molteno CD, Stanton ME, Herbert JS, Lindinger NM, Lewis CE, Dodge NC, Hoyme HE, Zeisel SH, Meintjes EM, Duggan CP, Jacobson JL.
Efficacy of maternal choline supplementation during pregnancy in mitigating adverse effects of prenatal alcohol exposure on growth and cognitive function: a randomized, double-blind, placebo-controlled clinical trial.
Alcohol Clinical and Experimental Research 2018 text