As we learn more about pregnancy, it is clear that the substances in cigarettes, alcohol and street drugs can all adversely affect a fetus. Stop using these substances completely well before you become pregnant—and definitely after you become pregnant. Your partner's use of these substances can also affect conception in some cases.
Cigarette Smoking
There's no doubt that smoking affects pregnancy and development of the fetus. Low birthweight and slow growth-rate problems occur in babies born to mothers who smoke. For your health and the health of your baby, stop smoking before you consider pregnancy.
Alcohol Consumption
My patients often ask if it's OK for them to drink alcoholic beverages "occasionally" during pregnancy, as long as they do not "abuse" alcohol by drinking a lot. In the past, we believed a little alcohol was OK during pregnancy, but now we know differently.
Most healthcare providers believe it's best not to drink any alcohol during pregnancy. Every time you take a drink, your baby does too! Stop using alcohol from the time you are preparing to conceive until after your baby is born.
Marijuana
Marijuana can be a dangerous drug during pregnancy. While some people think its side effects (to them) are mild, it truly can harm a developing baby. Marijuana crosses the placenta and enters the baby's system. A fetus exposed to marijuana before birth can have attention deficits, impaired decision-making abilities and memory problems in the childhood years.