Babies of mother, who smoke or are victims of passive smoking are more likely to be premature or may have low birth weight. It also increases the chances of having a miscarriage, a stillbirth, a malformed baby. The more you smoke or inhale the smoke, the greater is the risk for your baby, so quit smoking completely. Doctors believe that passive smoking has as much effect on the baby as direct smoking, so avoid smoky atmosphere in the house when you are pregnant. Drinking heavily in pregnancy can be serious for your baby.
Many drugs can be harmful or can have unknown effect on the baby.
So avoid taking medications in pregnancy other than the ones prescribed by the doctor, that too a doctor who knows that you are pregnant. If you have diseases like Blood pressure or diabetes, your doctor may have to alter your dosage. Wash your hands after cooking or handling raw meat. Don't eat under-cooked meat. It may contain parasites, which may seriously harm your baby.