You delete tobacco plant and medicines to be more fertile

The nicotine is another poison that affect at the same time to your well-being that to that of your son.
The drugs, be already social (as the marijuana) or for medical (as the antidepression medications) recipe they will also affect your capacity to conceive.
As much some as others can have short term benefits, such as being able to relax you or to reduce the stress, but unless you approach the actual questions that hide behind the stress, these problems they will simply return, leaving it to you in mental form and locked physics.

If you are making some prolonged treatment due to a chronic illness, ask to the physician on possible side effects of the treatment and you search some form of reducing the dose while you are trying to conceive and during the first studios of the pregnancy in the case of the women.