Risks versus benefits. Technically none of the antidepressants are officially approved for use in pregnancy. That being said many patients need these medications to function normally. In those cases the theoretical risk of exposure does not outweigh the certain need to take the medication. You and your doctor would discuss the situation and decide on a case-by-case basis if treatment is warranted.
Most are compadible. There are a variety of ssri medications & most fall into category c for pregnancy risk, meaning no human studies show a link with fetal defects although some animal studies are suggestive. They have similar cautions during breast feedings. The pediatrician should be aware of their ssri exposure as their alertness is often subdued for the first day or so. Discuss with your ob.